44 
PSYCHE 
[April 
NOTES ON SHORT EXPERIMENTS BEARING ON THE RELATION 
OF LARVAL TO ADULT LEGS. 
BY ALEC. ARSENE C.IRAULT, WASHINGTON, D.C. 
“The real relations of the adult legs to the larval legs are thus shown by 
Gonin. 
Tf 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 parts are 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ble of elongation; it may, on being withdrawn, give rise to the illusion that the 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 we cut off 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 Reaumur 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.’ ” “ 
F’rom the foregoing quotation, the following short experiments performed 
on the larvae of Heliothis ohsoleta Fabricius,^ 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-book of Entomology 1898 pp 654-655. 
b Formerly Heliothis armiger Iliibner. 
