Article beginning on page 44.
Psyche 12:44-45, 1905.

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PSKIf,?? . [April
EXPERIMENTS BEARING ON THE RELATION
F LARVAL TO ADULT LEGS
BY ALEC. ARSWE GIRAULT, WASHINGTON, B.C. *'The real relations of the adult legs to the larval tegs are thus shown by Gonin.
*If we carefully strip off the skin of a caterpillar near the time of pu- pation (Fig. 608 ), we see that the extremity only of the legs of the imago is drawn out of the larval legs; the other partsare pressed against each side of the thorax: near the ventral line a small pad represents the coxa and the trochanter; the femur and the tibia are distinctly recognizable, but soldered to each other and only separated by a slight furrow; they form by their union a very acute - knee or bend. The femur is movable on the pad-like coxa, the tibia continues without precise limits with the extremity concealed in the larval legs. The
three divisions of the latter do not appear to have any relation to the five joints of the perfect state. Under the microscope the rudiment appears very strong- ly plaited at the level of the tarsus, much less so in the other regions. A large
trachea penetrates into the femur with some capillaries; reaching the knee it bends into the tibia at a sharp curve, but does not become truly sinuous in approaching the extremity. It is then the tarsus especially which is suscepti- ble of elongation; it may, on being withdrawn, give rise to the illusion that the whole organ is disengaged from the larval leg. Even when w2 cut OR the limb of the caterpillar at its base, we only remove the tarsus of the imago; the femur and the tibia remain intact. From an evident homology Reaurnur has erroneously concluded that there is an iden- tity.
His opinion, classical up to this day, that the limb of the butterfly is entirely contained in the leg of the caterpillar, has been found to be inexact and should be abandoned*' " *
From the foregoing quotation, the following short experiments performed on the larva of Heliofhis of>su/c'/it Fabricius,b are easily understood. On the 20th of June at Paris,Texas, ten (10) full-grown larvae of this insect were taken from ears of corn and placed on fresh soil in the laboratory. They were ready to enter the soil. The anterior legs of each were immediately cut a Packard. A Text-hook of Entomology 1898 pp 654453.



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[April
1s shown by
time of pu-
he imago is
I side of the
trochan ter;
I each other
, very acute
a continues
legs. The
e five joints
Jery strong-
s. A large
the knee it
sinuous in
is suscepti-
ion that the
se, we only
act. From
s is an iden-
butterfly is
be inexact
s performed
f this insect
ory. They
diately cut
off with sharp scissors, taking care, during the operation, to remove the articu- -- -
- - - - - - -
-- -
- -
lated joints only.
The larvse were then allowLd to enter the earth, which six of them successfully accomplished during the following night. The remaining
four were found dead and were removed.
From these six larvae, three moths appeared on July 7th, following. Of the three, two had perfect legs. But the other had tu'o of the apical joints of its dextra//oret'eg I// /.j.~-/ng the third and last jozkt bearing the usual tdm l clan's. The conclusion to be drawn is obviously indicated by reference to the lines quoted.
Other experiments performed were failures because of the corresponding moths not issuing. The pupa of a larva whose legs had been amputated at the origin of the articulated joints;was dissected when some days old, and the half- formed m~th found with perfectly formed limbs. Two full-grown larva; were transferred to soil in a large glass jar and treated as formerly, but in addition to the articulated joints, a portion of the large lobe of the body to which the legs are appended was also removed, doubt- less injuring the so called histoblast. When cut, both of them jumped violently and a stream of dark liquid was ejected from the mouth. They immediately crawled off, however, when liberated seemingly not missing the pair of legs. The wounds bled for a short while, but healed the next day, then showing as large blackened scars. Although feeding voraciously, and apparently ready to pupate, both suddenly declined and died, and for lack of time the experiment was not repeated.
The percentage of moths successfully emerging from larvae thus mutilat- ed is very small, and it is vary ne.;essAry to use larger lots in experimtnts such as these.




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