Mass.) Marine Biological Laboratory (Woods Hole.

Biological lectures delivered at the Marine biological laboratory of Wood's Hole ... 1890-[1899] (Volume 5) online

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more developed complex showed a perfect union across the
wound. This was the case with every kind of tissue except in
the notochord, where a break sometimes occurred at the line of
the wound. For example, in a belly to belly union the liver cells
of one tadpole being in contact with those of the other, a com-
mon liver would be formed in the older complex. The same
was true for the nerve cord where an anterior half of one
embryo was joined to a posterior half of another embryo, in
normal proportions; a complete spinal cord resulted. Where,
on the other hand, different kinds of cell masses were in con-
tact, only a connective-tissue union occurred ; when, for
instance, a head was fused to the belly of a complete tadpole,
its well-developed neural cord ended abruptly, although connec-
tive-tissue cells formed a connection with the tissues of the
major component.

Owing to the interest aroused by Bern's results, the writer
endeavored to find another group of animals which would per-
mit of similar experimenting. Fortunately, the Lepidoptera
suggested themselves. Success was anticipated from the out-
set on general grounds, for the pupa of the Lepidoptera affords
an easily handled, quietly growing stage and one which pos-
sesses for the production of the imago within the pupal case
all the tissue-forming energy of an embryo. Furthermore,
beside the possibility of coalescence between two individuals
or parts of individuals, other very interesting lines of work
appeared ; namely, those bearing upon the production of the
often wonderful coloration of the wings. It had been shown
by the work of A. Mayer and others that the pigmental, as
opposed to the structural, colors in the wings of moths are
produced by the chemical decomposition of the haemolymph in
the empty scale cells. If, therefore, two pupae belonging to
differently colored species of moths could be made to grow
together and produce a pair of coalesced imagines, it would not
be unreasonable to expect from the mixed haemolymph at least
some sort of abnormal coloration, if, indeed, there did not appear
an actual color effect of each upon the other. Further support



EXPERIMENTS UPON THE LEPIDOPTERA. 221

for this assumption was found in the recorded instances of
hermaphrodite moths where dimorphic sexual coloration oc-
curred. Such a specimen, one of Saturnia io, the writer has
seen at the American Museum of Natural History in New
York. In this specimen the wings of one side are colored
like those of a male, those of the other like those of a female.
Oddly enough, the antennae and legs are correspondingly dif-
ferent in form. The interesting feature, however, is this: that
the orange color of the male is clouded by a faint purplish
overtone, and the dull female colors are considerably lightened
by a yellowish tinge. In other words, the male colors are
affected by the female half, and vice versa.

The problem of heredity involved is the question whether
the color and the gonad of a certain sex are both the effects of
a common set of causes, or whether the color is more directly
dependent upon the presence of a gonad of a certain sex. As
the color is produced by a chemical decomposition of the hae-
molymph, and as the haemolymph can hardly escape being
reciprocally affected chemically by the sexual organ that it
bathes, the second of the above possibilities would appear to be
indicated. The relation of these experiments to the subject of
internal secretion, recently put forward by Mathews, is quite
obvious. However, the data at present available are not suffi-
cient to warrant any hard and fast conclusion.

The pupae used in my experiments were those of Philosamia
cynthia, Samia cecropia, Callosamia promethea, and Teled
polyp/iemus, all belonging to the family Saturniidae. At first,
during the months of February and March, all experiments
were performed upon cynthia, in order to ascertain if any
fusion at all were obtainable. As the operated pupae in some
cases continued to live, success was reasonably assured and the
other species were then obtained, although in small numbers,
in order to determine the other facts; viz., the possibility of
reciprocal color effect upon each other of different species and
of different sexes. These latter pupae, however, had been
brought indoors at various times during the winter and spring,
and were consequently at different stages of advancement a
fact which materially lessened the chances of successful fusions.



222 BIOLOGICAL LECTURES.

In performing an operation, a strong, very sharp cartilage
knife was used. With a single clean cut a portion of a pupa
was cut away, and the remainder laid down with the wound
uppermost in order to prevent the escape of haemolymph
while the second component was prepared. The wounds of the
two fragments or components were then placed together, and
melted paraffine was applied to the edges with a camel's hair
brush. The paraffine on hardening formed a firm ring or band
which served the double purpose of keeping the component
parts together and of preventing the escape of haemolymph.
Wherever possible the operated complex was suspended in the
normal upright position, in cocoons cut to fit.

When in the successful cases the imagines were ready to
emerge, a state indicated by the looseness and dryness of the
papery pupal shell, it was necessary in almost every instance
to pick off the shell with a forceps, bit by bit. A few moths
came out independently. In either case the freed moths were
put in a box lined with netting, allowing them free room for
movement and expansion of their wings. Usually the wings
failed to expand to their full normal extent, probably owing to
the inevitable loss of haemolymph during the operation. Some-
times the wings of one component expanded, while those of the
other did not, depending apparently on the further development
of one beyond the other.

No attempt was made to feed or rear the moths. After
being allowed to live a few hours or days, they were chloro-
formed and dried for total specimens or preserved in spirit.
For sectioning purposes some were preserved in Perenyi's fluid
and in Graf's chrom-oxalate mixture.

The results fall naturally into three groups, according to the
operation and the relative size and make-up of the compound.
First, we shall consider those operations where portions of two
different pupae were united in normal proportions. In all
cases attempts to join lateral halves of two different pupae
were unsuccessful. Here the section passed sagitally a little
to one side of the median line. Although many of the com-
pounds lived in a plump, healthy condition for several weeks, all
ultimately died.



EXPERIMENTS UPON THE LEPIDOPTERA. 223



Better success was attained in joining an anterior end of
one pupa to a posterior end of another. Here the section was
made completely across the body just back of the posterior ends
of the wing cases. Altogether, sixty-one operations of this
kind were performed, affording but four living imagines. A
compound pupa of this kind is shown in Fig. i, a. Both parts
were from cynthia pupae. Three out of twenty-one cynthia



*




FIG. i. Operation of the first category, a, compound pupa; b, compound moth of
P. cynthia.



cases furnished moths, two of them emerging unassisted and
expanding their wings. One of these is also shown in Fig. i, b.
To a casual observer this specimen would appear quite normal.
The differences in general color and pattern between the ante-
rior and posterior parts of the abdomen are so slight as to be
easily overlooked. A rather curious condition appears in the
specimen. The posterior part of the abdomen was taken from
a male pupa, while the rest of the body was that of a female.
The result is that the eggs contained in the female portion
were too large to pass out through the male passages, and a



22 4



BIOLOGICAL LECTURES.



considerable bulge, noticeable even in the photograph, was
caused between the two portions of the compound abdomen.

Altogether, thirty-two attempts were made to unite in nor-
mal proportions fragments from two different species; only one
was successful. A hinder portion of a. promethea was perfectly
coalesced with an anterior part of a cynthia. This specimen is
shown in Fig. 2. Apparently, a perfect moth with unexpanded
wings confronts the observer. The contour of the abdomen
shows no break whatever. A point to be particularly noticed
is that the part of the compound abdomen taken from the




FIG. 2. Operation of the first category. Compound moth, wings, and anterior body
from cynthia ; terminal abdominal segments from promethea.

promethea shows no trace of a red color, but is buffy, exactly
as the general ground color of the rest of the abdomen, that of
the cynthia.

Summarizing, then, the results of the operations belonging
to this category, we find that out of twenty-nine cases where
the parts belonged to pupae of the same species, three imagines
were obtained. Where the fragments belonged to different
species, one out of thirty-two gave successful results.

A second group comprises the operations where a compound
of two pupae in "tandem " was prepared ; that is, the posterior
part of the abdomen of one and the anterior part of the body
of another pupa having been sliced off, the remaining fragments
were joined on a long axis. Usually the abdomen from the
fourth to the terminal segment was cut away from the anterior
component, but in some cases the section was made as far back



EXPERIMENTS UPON THE LEPIDOPTERA. 22$

as between the seventh and eighth segments. The section in
the posterior component varied within narrow limits, sometimes
passing far back of the eyes just anterior to the roots of the
wing cases, sometimes being anterior to the eyes. In many
cases, where but a little was sliced off, the posterior component,
especially if far advanced, simply healed over its own wound
and emerged independently, without the slightest attempt to
coalesce with its fellow pupa. Five operations of this kind
were made upon cynthia, with one successful coalescence. This
specimen is of the greatest interest. Unfortunately, a photo-
graph illustrating the important details cannot be taken, and
hence no illustration can be given. The interest lies in the
fact that from the posterior pupa of the " tandem " were cut away
the entire head, eyes, brain, and all, the basal portions of
the sacs of the antennae and mouth parts, as well as a portion
of the prothorax. The result is that in the coalesced moths
all of these parts are absent. The weakly developed antennae
and mouth parts of the hinder moth arise directly from the
narrow circular sheet of regenerated tissue which spreads from
the last abdominal segment of the anterior component to the
remains of the prothoracic ring of the posterior component.
The microscopic study of the internal conditions of this double
specimen will assuredly furnish some very interesting data.

The experiments of this group which would have been of
the greatest value, if successful, were those where male and
female promethea were united. Out of six operations not one
gave results, and hence no data for the determination of
reciprocal color effect could be here obtained.

Union of cynthia and promethea, however, gave out of six-
teen cases two remarkably fine fusions. One of these is shown
in Fig. 3. The components were both female, the prometJiea
being posterior. Unfortunately, the wings of both failed to
expand, although the moths lived for five days, until chloro-
formed. The other case was that of a female cynthia anterior
most firmly united to a promethea male posterior. The moths
of this compound also failed to expand their wings.

These two cases do not furnish any very definite data bear-
ing upon the color question. It is true that in the first case



226



BIOLOGICAL LECTURES.



there appears on the left posterior wing of the cynthia an
orange area from which the black scales are absent. Again,
the promethea is of a slightly lighter red than usual. In the
second case, moreover, both components are typically colored,
except that the body of the promethea shades posteriorly into
red, a characteristic color of the female only. Whether these
departures from the normal coloration are due to abnormal




FIG. 3. Operation of the second category. Union in " Tandem " of P. cynthia,
anterior, and C. promethea, posterior.

conditions resulting from the severity of the operations, or
whether they are produced by the mixture of the different
haemolymph, is not sufficiently clear.

The third group of operations is that producing "twins." In
these cases but little of either pupa was removed, so that two
practically entire moths, fused in various ways, result. Sixty-
nine pairs, altogether, were prepared, and fourteen of these
survived the metamorphosis.

Taking the divisions of this group in order, the first to be
noticed are the "head to head" unions. The pupae were sec-



EXPERIMENTS UPON THE LEPIDOPTERA. 22 7

tioned, as were the posterior components of the preceding
series. The resulting moths in the successful cases were
fused by their heads; where the section passed a little further
back, the prothorax was involved. Four successful fusions
were obtained between cecropia and cynthia, exhibiting, how-
ever, no abnormal colors in any of the components. One pair
of cecropia was perfectly coalesced. Another pair of cynthia
perfectly united presents a remarkable condition of the anten-
nae. The left antenna of one component arises from a com-





FIG. 4. Operation of the third category, a, united pupae, and b, united imagines
of S. cecropia.

mon stem with the right antenna, that on the same side of
the complex, of its fellow component. The fusion is so inti-
mate that the basal portions of the two antennae have fused
for a distance of over an eighth of an inch.

By cutting away some of the posterior segments of the
abdomen it is possible to produce " tail to tail " unions. Two
pairs of cynthia and one of cecropia were able to transform into
coalesced moths. Here, again, the internal relations will
undoubtedly present conditions of unusual interest.

Siamese twins, united back to back, were produced in but
one case. The dorsal portions of the pupal abdomina were cut
away. A united pair of pupae is shown in Fig. 4. The result-



228



BIOLOGICAL LECTURES.



ing moths, a very good pair by way of illustration, show a
broad bridge of union extending over the abdominal region
from the first to the fourth segments.

Two individuals united by their dorsal thoracic regions are
shown in Fig. 5. The posterior ends are turned in opposite
directions. This specimen, of no very great interest otherwise,





FIG. 5. Operation of the third category, a, united pupae and b, united imagines
of S '. cecropia.

illustrates the non-expansion of the wings of one moth, while
those of the other were of almost the normal extent.

Two moths can be fused by the wings by exposing the roots
of the pupal wing cases and uniting the wounds. In the one
successful case obtained both moths failed to extend their
wings, and no observations upon flight could be made.

In conclusion, it has been shown that it is possible to pro-
duce, by placing and keeping together the wounds of two sec-
tioned pupae or fragments of pupa, a very intimate coalescence
between the components. This coalescence is dependent upon



EXPERIMENTS UPON THE LEPIDOPTERA. 229

the regenerative or wound-healing power of the tissues involved.
So great is this power that in a " defect " cecropia example,
where the abdomen had been cut away back of the fourth seg-
ment and a paraffine film thrown across, the entire wound was
covered by a continuous and tough skin. This wound was a
half an inch or more in diameter.

It is more difficult to bring about a coalescence between
fragments of pupae belonging to different species or genera
than where the two components belong to the same species.
Out of 62 operations of the former category 7 cases resulted
favorably, about 11.2 per cent. From 95 operations of the
second kind, 14 were successful, a percentage of nearly 15.
The total number successfully brought through the metamor-
phosis was 21 out of 127 operations..

Considering the results in another way, the mortality among
the pupae of the first group described, parts united in normal
proportions, was greatest, the survivors being but 4 out of
6 1 6.5 per cent of the whole. The " tandems" come next,
with a total of 3 successes and 24 failures, n.i per cent;
the " twins," as would be expected, present the most favorable
figures, 14 out of 69, 20.2 per cent, pairs affording
coalesced imagines.

In regard to the second point, namely, the possibility of
reciprocal color effect, the results are somewhat disappointing.
With the exception of the two cases of cynthia and promethea
fusion, no departures from the normal color occurred. In none
of the cases of twin fusion of two specifically different moths
was there the slightest indication of abnormal coloration. The
entire question, therefore, as to whether a true reciprocal color
effect can be produced awaits the verdict of future extensive
experiment.



ELEVENTH LECTURE.



SOME OF THE FUNCTIONS AND FEATURES
OF A BIOLOGICAL STATION. 1

C. O. WHITMAN.

I HAVE a few considerations to offer on a subject not quite
new, but perhaps not without some interest to a society of
naturalists. The subject may be stated in the form of a
question: What are some of the more essential functions and
features to be represented in a biological station ? This ques-
tion is one that may fairly claim the attention of a society
organized for " the discussion of methods of investigation and
instruction, and other topics of interest to investigators and
teachers of natural history; and for the adoption of such
measures as shall tend to the advancement and diffusion of the
knowledge of natural history."

I know of no other organization in this country in which the
different sides of biology are more fully and widely represented,
and no other in which the discussion of such questions as I
have stated has been more explicitly invited.

The question before us, as you perceive, is one of ideals,
something which we can construct without the aid of an endow-
ment, and probably without any permanent loss of protoplasm.
And yet, what I have in mind is not wholly imaginery, for it
has some basis in experience and in acquaintance with some of
the best models.

Let us first of all try to get at some general principle which
may serve to guide our judgment of ideals, and by the aid of
which we may be able to formulate an answer to the question
proposed.

1 Presidential address prepared for the Ithaca meeting (1897) of the Society of
American Naturalists.



232 BIOLOGICAL LECTURES.

As all will allow, ideals are absolutely indispensable to
progress and always safe, provided they are kept growing.
Like all biological things, live ideals originate by germination,
and their growth is subject to no limit except in mental petri-
faction. Growth and adaptability are as natural and necessary
to them as to living organisms. Here we have, then, an unfailing
test for the soundness or relative merit of ideals. Seeds may
be kept for years without sensible change or loss of power to
germinate. But it is because they are kept, not planted and
cultivated. Once planted, they must grow or rot. So it is
with ideals. The unchanged ideal that we sometimes hear
boasted of is at best but a dormant germ, not a plant with
roots and branches in functional activity. If an ideal stands
for anything which is growing and developing, then it must
also grow, or be supplanted by one that will grow. It is easy,
of course, to conceive of ideals a hundred years or more ahead
of possible realization; but such ideals could have no vital con-
nection with present needs, and long before the time of possible
realization, they would cease to be the best, even if the best
conceivable at the start.

We are here, then, concerned only with ideals rooted in
experience and continually expanding above and in advance of
experience. The moment growth ceases, that moment the
work of the ideal is done. Something fails at the roots, and
you have waste mental timber to be cleared away as soon as
possible to make room for the new seed.

Let us here take warning of one danger to which we are all
liable, the danger of adopting ideals and adhering to them
as finalities, forgetting that progress in the model is not only
possible, but essential to progress in achievement. The danger
is all the greater in the case of ideals lying outside our special
field of work, which we are unable to test and improve by
our own efforts. The head may thus become stored with a
lot of fixed mental furniture, and the possessor become the
victim of an illusion, from the charms of which it is difficult
to disenchant him. He falls into admiration of his furniture,
taking most pride in its unchangeableness. It was, perhaps, the
best to be found in the market at the time of installment, and



A BIOLOGICAL STATION. 233

he finds pleasure in the conceit that what was the best is and
must remain the best. He sees new developments in the
market, but his pride and inertia content him with the old.
The illusion now takes full possession of him, and every depar-
ture from his new ideals seems like abandonment of the higher
for the lower standard of excellence. His conceit grows instead
of his ideals, and every annual ring added to its thickness
renders it the more impervious.

Can any one say he has never met this illusion ? Then a
warning may have more pertinency than I should have ventured
to claim for it.

To conclude these introductory remarks, let me again empha-
size the all-important qualification of the sound ideal and name
the prime condition of its usefulness. The qualification is
vitality and the capacity for unlimited growth and development.
The condition is absolute freedom for growth in all directions
compatible with the symmetrical development of the science
as a whole. Please remember that the question of means does
not now concern us. We must first get at principles, leaving
details of execution to be worked out afterwards in harmony
therewith. No one can foresee what means may be found, and
it would be a waste of time to try to decide what should be
done under this, that, or the other set of conditions. If we
know our ideal, we know the direction of effort, and through
the effort, the means are eventually found.

It will help us in the formulation of our ideal if we glance a
moment at the ideals that have found most favor. The best
models of marine laboratories ten years ago all agreed in mak-
ing research the exclusive aim, and in limiting the work to
marine forms. In most cases the work was still further limited,
embracing only marine zoology, and often only a small portion
of that field. The idea of representing all branches of even
marine biology was seriously entertained nowhere except at
Naples. Remembering that marine laboratories were first
introduced only about a quarter of a century ago, we are not
surprised at these limitations. Even the narrowest limitations
were extensions beyond what had been done before. The
Naples station itself began as a zoological station, and still



234 BIOLOGICAL LECTURES.

bears the name Stazione Zoologica. But the earlier ideal was
not long in expanding so as to include both physiology and
botany. Will its growth stop there ? I do not believe it will,
but that remains to be seen.

Our own seaside schools, introduced by Louis Agassiz at
Penikese and continued by Professor Hyatt at Annisquam,
combined instruction with research, and this plan was adopted
at Wood's Holl in 1888. Instruction, however, was accepted
more as a necessity than as a feature desirable in itself. The
older ideal of research alone was still held to be the highest,
and, by many, investigation was regarded as the only legitimate
function of a marine laboratory. Poverty compelled us to go
beyond that ideal and carry two functions instead of one. The
result has been that some of us have developed an ideal of still
wider scope, while others stand, as they began, by their first
choice.

We have, then, two distinct types of ideals, the one includ-
ing, the other excluding instruction. One is preferred for
being limited to investigation; the other is claimed to be both
broader and higher for just the contrary reason, that it is
not limited to investigation. At first sight it might seem that


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Online LibraryMass.) Marine Biological Laboratory (Woods HoleBiological lectures delivered at the Marine biological laboratory of Wood's Hole ... 1890-[1899] (Volume 5) → online text (page 19 of 20)