178 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Many soft-shelled animals were obtained by keeping young crabs in 
aquaria, and feeding them freely until ecdysis took place. 
Lobster larve were hatched at the U.S. Fish Commission Station, 
Wood’s Hole, during June and July. They were reared, but with 
great difficulty, up to the eighth moult. Fed on minced crab’s liver 
they throve well; but unfortunately they also fed indiscriminately on 
each other. 
Crangon was found in large numbers in the muddy bottom of the 
Charles River ; crayfish were bought in the New York City markets. 
2. Methods. 
In sectioning, great difficulty was experienced, both on account of 
the thickness of the chitin, which was often calcified, and because of 
the siliceous otoliths, so numerous in the sacs of Macrura, and glued by 
secretions to the hair tips. As the otoliths are insoluble in acids strong 
enough to completely destroy organic tissues, the only successful 
remedy was to remove them mechanically. This was best accomplished 
by washing them out by a stream of water blown into the sac. The 
apparatus for this consisted of a short piece of small rubber tubing into 
one end of which was inserted a glass tube drawn out to a fine point. 
The other end of the tubing being held in the mouth, and the capillary 
tube inserted into the aperture of the otocyst, a stream of water was 
driven into the cavity of the sac with considerable force. The larger 
otoliths having been washed out in this way, fairly good sections could 
be cut. 
In the crab, the difficulty in cutting the very thick calcified chitin 
was obviated by using soft-shelled animals. The chitin is at this stage 
very thin, uncalcified, and therefore more readily sectioned. Lobster 
and crayfish antennules were decalcified by placing them in Gilson’s 
fluid for twenty-four hours, or in Vom Rath’s platinic-osmic fixative 
for a week or ten days. 
Of the many fixing reagents used, (1) Vom Rath’s platinic-osmo-picro- 
acetic mixture, (2) his corrosive-picro-acetic fluid, and (3) corrosive 
sublimate plus 1 % acetic acid gave the best results and in the order named. 
The last two were followed by staining in iron haematoxylin, which 
gave a clear definite stain of sections as thick as 20u. The platinic- 
chloride fixative of Vom Rath was used for from three to five days, either 
followed or not by treatment with pyroligneous acid. In Palzmonetes 
and Crangon a fine differentiation of fibre tracts was obtained by using 
~ 
