December 3, 1970
by Wilbur Norton Vroman
Assembly Room, A. K. Smiley Public
paper could have been titled, To Reproduce. In the literature on reproduction, biologists
use, as do all professionals, a language of their own; the word, 'replicate' indicates to
make a copy of itself, to reproduce.
related themes run through the paper:
The curiosity that all people have concerning reproduction as it is illustrated by
experiences in my own childhood.
The need to reproduce sexually if a species is to
have those slight variances in offspring necessary
for-it to adapt to changing environments.
The emergence of bizarre and divergent sexual behavior
among some of the invertebrates.
0 R E P R 0 D U C E
years ago I was invited to an evening meeting of some very learned writers. In this group
of writers was such talent as Dr. Lawrence Nelson, Dr. Louis Mertins, and Mrs. Bess Adams,
Glenn's capable wife. With the inclusion of the four-letter word in contemporary writing
and with the anticipation of the sex act as the main course, rather than the spice, in
best selling fare, I did not expect much embarrassment over the program to be evidenced by
the members of this writers' guild. The program was to be an illustrated talk on sexual
reproduction. There were many who were not writers at this meeting, however. With me was
my wife, who had lived the sheltered part of her life in a Baptist parsonage. There were
in the group several spinster ladies and some missionaries' widows from Plymouth Village.
There were several prudes and shy perons like myself, who blush and who are compelled to
turn our heads when walking through the lingerie department at Harris'. These could be
expected to be somewhat uncomfortable if just the two words, "sexual
reproduction" were to be said aloud.
a picture is worth a thousand words, then, at that meeting, the words "sexual
reproduction" must have been said in the tens of thousands of times; it was a program
of colored slides on sexual reproduction, on insects and other invertebrates in the act of
copulation. It should have embarrassed my sheltered wife, the spinsters, the missionaries'
widows, and even me, the declared shy prude. It did not. I was more than interested and
pleased by the pictures.
pictures were shown by one of Redlands' own, a gentleman of English birth, and they were
shown with a delicacy which made the presentation almost one of poetry; and that is not
always the case with many of Ed Fisher's presentations. I would that my words had the same
delicacy and refinement and beauty in composition that Mr. Fisher has in his pictures
since I have chosen the same subject, Sexual Reproduction, the need for it in nature, and
the methods of some of the invertebrates.
I was a very young boy I was given a Gilbert Chemistry set by Santa Claus. Among the
chemicals was oxalic acid. I now made a solution of the powder and placed it in a saucer.
In a few days, I was surprised to find some beautiful needle-shaped crystals in the dish.
I ground the crystals to a powder, dissolved them and, in a few days, again found the same
pre-adolescent scientific enthusiasm, for an entire summer I ground oxalic acid to a
powder, dissolved the powder and formed crystals. I wanted to see if, just for once, some
other crystal shape would be formed. Of course, none did; but I did prove something to
myself: oxalic acid crystals produce only oxalic acid crystals unless something new is
added. Second, oxalic acid crystals do not survive if they are ground, or heated, or have
water poured on them. They did reproduce themselves, but they did not produce variants nor
additional crystals. And, while they grew, they did not live. And, while they were always
oxalic acid crystals, they could not be formed unless oxalic acid was already present in
juvenile bit of research is a far cry from the sophisticated research into the life
processes made by today's molecular biologists. They have divided the cell into a series
of components, each of which seems to perform its unique process, be it to take food in
and convert it into useable energy and to excrete waste materials, or to take food in and
convert it into complex proteins and nucleic acids and, through DNA, deoxyribonucleic
acid, to reproduce,
? to replicate is the term biologists use, ? to replicate the cell and to pass omits
inheritance. It is beyond my comprehension.
oxalic acid did seem to replicate itself but it lacked something, the life process. It
lacked the ability to take in chemicals and from within itself to convert the chemicals to
my post-adolescent days I received a small microscope as a Christmas present, ? I no
longer believed in Santa Claus. I could watch the single-celled animals, the amoebas and
paramecia, move about, engulf food and grow. I was most excited when I saw an amoeba split
into two daughter cells, ? or, should they be called "sister cells"?
water dried on the microscope slide and as it dried, all of the sister amoebas died. They
were unable to adapt to the changing environment. Perhaps, if there had been a slight
change in their structures, if there had been some change in the factors for inheritance,
they could have adapted to their dry environment - gone to sleep - and recovered when
was excited: I had seen the amoeba reproduce; however, it was by fission and it had had
its limitations, there had been no sexual reproduction that could have changed the factors
for inheritance. The inheritance was from a single parent and, with the exception of
slight mutations, the amoebas would produce daughters, or sisters, that were literally
"chips off the old block"; they had been doing it for millions of years, and
would continue to do so for millions of more years unless the environment becomes too
things are comprised of millions of cells, are most complex, and specialized structures.
This fission method works satisfactorily for the simple cell, but it becomes a cartoon
when it is applied to a whole complex animal. Picture an elephant splitting itself through
fission, through asexual reproduction, into two faithful, better than Xerox, replicas of
fission process works well in higher plants and animals, but only for the individual cell
units; the corpuscle splits into two corpuscles, et cetera. It produced little or no
variance in individual cells so that they could adapt to changing environments. To divide
a many-celled flea, or fly, or elephant, or man, by splitting,becomes ridiculous. Unless
Mother Nature maintained a constancy and a contentment with the one-celled creatures, she
would have to develop variances within creatures and less awkward methods of reproducing.
Through one of the eons of the millions of eons available, two types emerged: the rooster
and the hen, the bull and the cow, the boy scout and the girl scout, the male and the
female. Necessary sex reared its ugly, and more often, its beautiful head.
word "sex" is derived from the Latin, sectus,
which means separation. It defines precisely the division of a species into two types, the
male and the female. The male produces the spermatozoa, the sperms; the female produces
the ova, the eggs. The union of these two is the method by which Mother Nature resolves
the problems created by changing environments and the reproduction of complex creatures.
asexual reproduction, such as I had observed in the amoeba, the same individual persists
indefinitely; the thousandth generation is the first generation. There is practically no
variance between individuals and very little ability to adapt to changes. "The sexual
processes, on the other hand, are not only far more general, but imply a fresh combination
of the gametes, the spermatazoa and the ova
(when) they are brought together in the act of fertilization. In this act a new
individual with a new potential is formed, one that bears the hereditary characters of
both parents associated in a new arrangement different from that of either
certain refinements, the spermatazoa and the ova which carry the inheritable factors of
the parents, evolve in the testes and the ovaries by a simple cell division, much as the
amoeba on my slide had divided. What does happen in the cell division of the gametes is
almost miraculous: The process is called meiosis. The inheritance factors are carried in a
part of the cell chromosomes ?
called because they are bodies within the cell that can be dyed. Without going into
details, the chromosomes divide and, in a process common to all germ cell division, the
number of them is reduced to one-half through a shuffling arrangement. In the opposite
sex, the gametes have their chromosomes reduced to one-half. Meiosis varies between the
sexes so that many times as many spermatazoa are formed as are ova. The male factor is
expendable: At the time of fertilization, the gametes are fused to form a cell with a
full complement of chromosomes; and variability and possible adaptability to a changing
environment takes place.
methods by which the union of the spermatazoa and the ova take place, fertilization, must
have exhausted Mother Nature's ingenuity. They are various, and to man, strange and
interesting. They may be casual and haphazard as in the oyster, or they may involve the
ritualistic and complex lovemaking of man.
most of the invertebrates that live in the sea, fertilization may consist of the random
shedding of the sperms and the eggs. In this external fertilization, vast numbers of
eggs and sperms must be produced to increase the odds of a sperm reaching an egg. There is
a vast waste of the gametes and, since the eggs carry a food supply, a tremendous drain
has been placed upon the female.
Nature has been given millions of years in which to develop efficient methods by which the
sperms and the ova can be brought together. In the case of the careless and haphazard
oysters, some will release their sperms and ova only in the presence of certain chemicals
in the ocean. Those oysters in the immediate area of the chemical will be stimulated to
shed their gametes. Much is left to chance even with this remarkable advance.
more precise method of stimulation of the sperms and ova and fertilization is evidenced by
the spawning of the grunion on our Southern California beaches. The stimulant is the tide.
When the tide is right, the grunion come to the beaches. The male grunion encircles the
female and fertilizes her eggs as she lays them. The female lays the eggs in the sand at
the correct distance up on the beach to prevent them from being washed out with the waves
and yet they are laid close enough to the water's edge so that the next highest tide,
about a fortnight hence, will carry the newly hatched grunion out to sea.
is still much of a chance that many eggs will not hatch, but this method of one of the
vertebrates is much better than that of the oyster, an invertebrate.
improvement in the hit-and-miss method of fertilization was made by the sea urchin that
used to be common on our local beaches: a mature sea urchin releases a stimulant when
either ova or sperms are ready; the presence of this stimulant causes all sea urchins
close by to ripen and release their ova and sperms at about the same time. It becomes
epidemic: Fertilization is more assured by this method. There is, however, a great waste
of fertilized eggs. Mother Nature probably used a couple more million of years to develop
more efficient mothods; and she developed many methods between the random shedding of ova
and sperms as in the oyster, the more specialized and precise method of shedding of sperms
and ova in the sea urchin and grunion, until she developed true internal fertilization.
I became a young man, I moved to California and, as are all Midwesterners, I was
fascinated by the creatures that abound in the salt water beaches. I liked to probe into
the mouths of the many-colored anemones.
extended tentacles would close tightly over the mouth and the anemone would lose its color
and become indiscernable on the shallow floor of the ocean pond. While the anemone does
not have true internal fertilization, it seems to be heading in that general direction.
a sea anemone is cut in half, it shows an internal central cavity. The ripe eggs are
discharged into its own central cavity by the female anemone. When this is done a chemical
stimulant is released. The free swimming sperms of other anemones are attracted by this
stimulant and move into the mouth of the female and thence into the central cavity to
fertilize the eggs. The fertilized eggs remain in the female, develop, and, at a certain
stage "hatch" and swim out of the mouth of the female under their own power.
Stillman Berry of our club may have to verify this, but it is my understanding that the
reproduction in clams is similar to the reproduction in the anemones.
span of life has been so long that I witnessed, in my early childhood, the last of the
medicine shows. I can remember the vendor of some mysterious elixir holding up a bottle
that he professed contained a five foot tapeworm that had come out of the intestine of a
boy, a boy who had been treated with the all-powerful elixer that the "medicine
man" was vending. The bottle was passed around; it was repulsive and yet fascinating
to me. In my nightmarish sleep that night, I had convinced myself that there was not such
a creature as a tapeworm. (My mother had assured me that the medicine man was a fake.) It
was not until a course in physiology warned against under-cooked pork that I believed in
the existence of a tapeworm.
life cycle of the tapeworm is an interesting adaptation to sexual reproduction. The host
animal, the pig, in its routing, swallows fertilized eggs of the tapeworm. The eggs hatch
within the body of the host animal and develop
tapeworms. The head segments of the tapeworm have the male organs and tail pieces, the
female organs and the eggs. The mature sperms are set free into the intestine. They swim
down and are passed along by the natural contractions of the intestine until they find a
tail segment of a tapeworm that is full of mature eggs. Fertilization takes place in this
segment; the segment breaks off from the parent animal and is passed out of the host's
body to the ground. And the cycle starts again.
fertilization of the eggs by the sperms seems to be internal fertilization. (It is
internal to the pig.') It is not internal fertilization. In true internal fertilization,
the male places the sperm into the female's tract. In true internal fertilization, while
it may not seem so to human eyes and human values, some sort of preliminary courtship is
fertilization is possible only if there is a cooperative female even within the lower
animals, the invertebrates. The female must be wooed by the male into cooperation, into a
willingness to mate. As a part of this courtship, the female must be maneuvered into a
position where she can receive the sperm from the male. Courtship is necessary to have
the female both willing and able to have internal fertilization.
are many forms that courtship and internal fertilization take. An unusual type of
courtship is that of the mole crab:
mole crabs of the Atlantic Coast go through a ritual which induces the female crab to stay
still long enough for the male to deposit his sperms. One pair of the male's legs are
adapted for holding on to the female. When the female comes out of her burrow he holds on
to the female long enough for him to weave a ribbon full of sperms on her underside. When
the female lays her eggs they come into contact with the sperms in the ribbon. While this
ritual is a form of courtship, it is not true internal fertilization.
have a different type of courtship from crabs. The sperms are not placed in ribbons on the
female's underside. "During mating, they are transferred into a special receptacle in
the female's body where they are stored until she lays her eggs. To get these sperms
stored is a difficult procedure. Through a courtship procedure, the male gets the female
to lie on her back. He locks her legs and pincers with his large claws. His first pair of
swimmerets have been formed into a duct. These are placed into the female's receptacles.
The male has to use a pair of his walking legs to direct these modified swimmerets into
the female's receptacles. After they are inserted, the sperm and mucous are passed into
this storage receptacle. Having placed his sperm, the male lobster goes away.
female rights herself and waits until she is ready to lay her eggs. When she lays her eggs
she also squeezes the sperm from her storage receptacle. She literally mixes the sperms
and ova with her swimmerets. She carries the fertilized eggs around with her for ten
months, until they finally are hatched." While the sperms are placed by the male
inside the female, in the lobster, as in the mole crab, fertilization is external.
what seems to man as cruel, one of the sea worms has developed a courtship ritual to
assure internal fertilization. Through an external stimulation at spawning time, the
female bites off the tail segment of the male during the mating rites. This segment
contains the mature sperms. Fortunately, the male can replace the lost section by
parthogenic reproduction. The male has the gruesome pleasure of watching the female eating
his tail section: He'll have his revenge later, however. After the female's digestive
juices have dissolved the male segment, the spermatazoa are freed into the
intestine of the female. Aggressive sperms that they are, they bore
through the wall of the intestine into the body cavity of the female. Within this cavity,
they find the ripe eggs and fertilize them. Then, for some reason -- and here is where the
male gets his revenge -- the female's body splits and the eggs escape into the sea. This
is an example of courtship with internal fertilization.
years ago I was a Boy Scout. On our scout hikes we liked to go swimming in the nude in the
Little Vermillion River. I had fun swimming in the old swimming hole, but when I
cameout, I found that leeches had fastened themselves to my legs. To this day, there are
few things as repulsive to me as a leech. And its sex life is just as repulsive. The male
leech's sperms are enclosed in a sac. The sac and the sperms together are called a
spermatophore. This spermatophore is glued, by the male leech, on to some part of the
female's back. There is an irritant in the spermatophore which causes an ulcer to form on
the skin of the female leech. The sperms swim out of the spermatophore through the open
sore into the body of the leech. The ulcer heals over. The sperms, now in the body of the
female leech, travel to the ovaries, where they fertilize the eggs. What an unattractive
way for an unattractive invertebrate to perform internal fertilization)
Michelmore of England, in her book, Sexual Reproduction, writes of a "strange
animal called Peripatus, intermediate . . . .between the segmented worms and the insects.
Some forms of Peripatus attach a spermatophore to the female's back just as the leech
does. Again an ulcer forms and the sperms enter the female's body cavity, making for the
ovaries. The sperms appear to have a function that is an addition to the functions of the
sperms of the leech. The first sperms to arrive cause ovulation to take place,
then they die. Fertilization takes place only if the sperms from another spermatophore
varieties of Peripatus have improved on this method of mating. Sometimes infections are
caused by the ulcers. While it still is unpleasant, one of the methods of mating does
lessen the risk of infection. The male's reproductive duct ends in a sharp spine which he
drives through the female's skin. He then places the sperms directly in the female's body
cavity and the sperms travel to the ovaries.
am always amazed at the number of earthworms that dry up on Redlands' sidewalks after each
heavy rainstorm. They must be very prolific. The earthworm has an unusual method of
earthworm is a hermaphroditic animal; it is both sexes. Since it is hermaphroditic, any
other earthworm will serve as a mate. The earthworm simply crawls across another
earthworm. It is a matter of maneuvering until the sperms of one of the worms can get to
the eggs of another and vice versa. The earthworm has no arms or legs to hold itself into
mating positions. It was necessary to develop some other technique to hold two earthworms
an elementary biology class in high school, I had to dissect an earthworm. There is one
section which looks like a little saddle on the worm. When the worms mate this saddle
adheres to the ninth and tenth segments of the other worm. This sticking together of the
saddle of one to the gonad sections of the other is accomplished by driving bristles into
the other worm. A groove is formed between the worms. During mating, the sperms travel in
opposite directions down the groove to the ovaries of the other worm. After fertilization,
the worms separate. The mucous material forms a case around the eggs and each worm. The
case works forward and slips off the head of the worm to form a capsule containing the
Michelmore cites another odd method of mating. On the Pacific Coast, there is an
hermaphroditic shell-less snail called the sea hare. "In the breeding season, one sea
hare mounts another and they mate. Unlike the earthworm they do not exchange sperms. Where
the procedure is unusual is that the top sea hare, itself, may be mounted, so that it is
giving sperm to sea hare A and at the same time receiving sperm from sea hare C. The
process becomes somewhat bizarre when as many as seven or eight animals become involved at
once, the final touch being when the one at the head of the line swings around to mount
the one at the tail, forming a strange reproductive circle." 4 Who is doing what to
the methods of mating cited above may seem crude, ridiculous, or even cruel, some of the
mating procedures of invertebrates develop a refinement and gentleness.
are related to spiders. Before they mate they perform a dance that is very involved and in
which both mates play a part. The male grasps the female with his pincers and holds her.
He then secretes a spermatophore containing his sperms. It is shaped like a round-headed
map pin. The male manipulates the spermatophore until it is directly beneath a sexual pore
on the female. The female opens her sexual pore and takes the spermatophore that the male
is holding, into the sexual pore and into her body cavity. Once near the eggs, the
spermatophore releases the sperms to fertilize the eggs.
my daydreaming days, I would lie on my back and watch dragonflies hover around my mother's
lily pool. Sometimes a joined pair, in tandem formation, would land. I knew they were
mating but I did not know how it was being done. I actually had the two sexes reversed.
After considerable acrobatics, the dragonflies got into a tandem position. After landing,
it was the female who bent her body forward and inserted into a pore on the male.
this pore was a spermatophore. The male dragonfly held onto the female until all of the
sperms in the spermatophore had been released into her body. Instead of the sperms being
placed in the female dragonfly by the male, it was the sperms being taken out of the male
dragonfly by the female.
do not remember any land snails in my growing-up days in Illinois. One of my first
experiences with them was in observing a gentle neighbor lady.in Red I watched her
wandering around in her iris bed one night with a flashlight. I asked her if I could help
her find something. She told me that she was killing snails. Armed with a box of Morton's
salt, she would find a snail with her flashlight and then she would sprinkle salt on it.
I, too, was fascinated by the way the snail would boil and dissolve.
was not until I had seen Ed Fisher's pictures that I learned of the cupid's dart method of
mating of the hermaphroditic snail. Quoting from Susan Michelmore: " . . . .the land
snail also goes to great lengths to ensure reciprocal mating. In fact, the mating of the
snail has some points in common with that of the leech described earlier in that the
sperms are contained in spermatophore and the animals stimulate one another by hypodermic
injection. In the case of the snail it is not the spermatophore that is injected: the
process is even more complicated. At the end of their reproductive tracts,snails have a
dart sac which contains the dart,a sculptured calcareous weapon, which they can eject at
will. When two snails are almost in contact, just prior to mating, they expel their darts
with great vigor from the openings of their female ducts into their partners' bodies.
These darts enter with such force that they often become imbedded in the animal's gut or
other internal organs. This drastic action seems to provide sexual stimulation and they
approach one another and exchange spermatophores."
spermatophores are stored in the female parts of the snail until the ova are ripe. The
covering of the spermatophore has gradually
dissolved and the sperms are released to fertilize the eggs.
development of the spermatophore was a great advance over the random scattering of sperms.
There are still many hazards in transferring a bag of sperm from the male to the female.
The future of the species could be more assured if a pipeline could be developed from the
male to the female. Through the years, Mother Nature improved the process of reproduction
" . . . .by the development of the end part of the male's reproductive tract into a
special mobile sperm-carrying duct, the penis. There is a corresponding modification . of
the female's duct to form a special pocket, the vagina, into which the penis fits."
type of mating is not too common in the invertebrates although it is found in insects. To
human eyes, mating of insects often seems most awkward and complicated. The penis of
insects generally points backward and must be reversed in direction before it can enter
the female. The simplest of the contortions necessary before insects can mate is for the
male to alight on the female's back and then to curve his stomach around to point the
insect's penis is an armored, rigid organ. In addition, in insects, for some reason, the
bottom surface of the penis generally has to be the uppermost surface when entering the
female's vagina. The sex organs also have projections and bristles on them. It is also
important that the female insect's body remain undistorted. All of this seems unnessarily
complicated yet it is a method by which Mother Nature has maintained the many species of
paper does not intend to carry sexual reproduction beyond the invertebrates.
It is of interest to note that birds and reptiles also have internal fertilization and
that some of them have developed a penis to assist in this process. Some lizards, all
flightless birds, and ducks have a well developed penis.
was surprised, not so many years ago, to come across a case in a museum in Salzburg,
Austria, that contained a collection of penis bones. I had not known until then that in
some mammals, where the mating period is relatively long, a penis bone has been developed
to maintain the rigidity of the penis. These bones are found in wolves, dogs, foxes, mink,
walrus, and the whale.
paper has attempted to show that the consistent reforming 8f identical crystals from an
oxalic solution is not reproduction. It has attempted to show that to reproduce by fission
may work adequately for simple organisms, but it would not work for a complex elephant. It
has attempted to show that there must be an opportunity for the re-combination of the
factors of inheritance if an animal is to adapt to changing environments. It has attempted
to show that internal fertilization is a more efficient method of conserving sperm and
eggs than is the random scattering, as in the case of some of the sea creatures.
paper has hinted that Mother Nature, in a seeming lack of direction, has developed many
bizarre and cruel methods of mating, both in courtship and in the fertilization of the
eggs. It has also hinted that this lack of direction has resulted in the many species of
insects. In review: this paper has told of sexual reproduction in oysters, grunion, sea
urchins, anemones, tapeworms, crabs, lobsters, sea worms, leeches, Peripatus, earthworms,
sea hares, pseudoscorpions, snails, dragon flies, and insects.
am glad that I am a naked ape; but what if I had been a horse fly: