110 Wisconsin Academy of Sciences , Arts, and Letters. 
at such a time very few pupae will be found, but numbers of 
larvae in an inactive state may be seen. Several days seem to 
be necessary for pupation after closing the case. The first adult 
was reared about March 15. On April 18 many adults were 
taken beneath the stones about the springs and at the same 
time many eggs were found. Probably some were out as early 
as the first of April. 
Gross dissection was found practicable as a means for much 
of the work done, the respiratory system being worked out en¬ 
tirely in this way. The full grown larvae,—in the last instar— 
average about 16 mm. in length by 3% in breadth of abdomen. 
The greatest hindrance to dissection w r as encountered in the 
numerous leaf-like fat bodies with which the organs are sur¬ 
rounded. In a few specimens dissected after being dead a few 
hours the fat bodies could be washed out easily by means of a 
pipette. For microscopic preparations the common fixing agents 
and stains were used. Delafield's haematoxylin was found serv¬ 
iceable in staining the nuclei of the spinning glands, for whole 
mounts of the same. These glands, after fixation, may be split 
with a fine scalpel along one side and spread out. This shows^ 
the whole area of the surfaces of the cells and gets rid of the 
secreted mass of silk within the lumen, wdiich, taking the stain, 
would otherwise obscure the nuclear structures, A rather long 
exposure to the haematoxylin is necessary to penetrate the nu¬ 
clei of such cells. The cytoplasm is thus stained a deep blue 
which must be washed out with acid alcohol. The addition 
of a counter stain, such as eosin, rather tends to obscure the nu¬ 
clei than to aid in differentiation, owing to the thick mass of 
cytoplasm. 
Respiratory System.— The internal respiratory system 
consists of two large longitudinal tracheae extending throughout 
the body and lying in a series of curves, each the length of a 
segment. (Fig. 1.) Each trachea has connected with it a 
series of smaller branches which pass to the external respiratory 
filaments and to the various organs and muscles of the body. 
In the prothorax each longitudinal trachea divides into two- 
large branches which pass forward into the head, entering at 
different levels. Before entering the head each of these again 
