ANNALS 
OF 
The Entomological Society of America 
Volume VII §-U-NoEF ES 14 Number 2 
A STRUCTURAL STUDY OF THE CATERPILLARS: 
lil, THE SOMATIC MUSCLES. 
Wo. T. M. Forpss, Ph. D., Worcester, Mass. 
In consideration of the very few dissections of the muscular 
system of Lepidoptera which have been published, and their 
radically different interpretation, it has seemed advisable 
to study a few more forms and trace if possible the points of 
disagreement. 
PREPARATION. 
A serious matter in such a research is the preparation of 
material. The muscles are small and slender, quite difficult 
to trace without a good microscope and plenty of light, easily 
broken in dissection in hardened material, and almost per- 
fectly transparent when fresh., Besides this they do not 
differ in color from the fat with which they are intermingled, 
and when preserved in formalin hardly differ in consistency. 
The most satisfactory material was opened out after killing 
with cyanide, and pinned out on a piece of cork; then treated 
with strong corrosive sublimate (bichloride of mercury) and 
dissected while immersed in a dilute solution of the sublimate. 
This makes the muscles intensely white, distinguishable from 
the fat by their silky luster; but the mercury attacks dis- 
secting instruments badly and so most of the work was done 
with material preserved in formalin (4 per cent., that is, 10 
per cent. of the commercial solution). Alcohol was also 
tried, and was nearly as good; the muscles being darkened 
109 

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