No. 467.] ZOOLOGICAL MATERIAL. 789 
normal salt solution (0.75% NaCl). In the absence of living 
specimens, chromic-acid specimens do fairly well for the circu- 
latory system. 
For sectioning with a microtome it is necessary to have speci- 
mens with intestines entirely free from grit. Worms that have 
been kept in clean, moist muslin for a considerable length of 
time will usually be found to have the alimentary canal free 
from all undesirable substances. The muslin should be 
changed every day, and the worms must not be fed. A quicker 
method ! is to flush the alimentary canal by means of an injec- 
tion apparatus. Use a cannula with a rather large opening ; the 
proper pressure must be determined by experiment. Stupefy 
the worms with dilute alcohol (3 to 6%). Inject the alimentary 
canal from the posterior end with 0.75 % salt solution ; roll the 
body of the worm back of the clitellum between the fingers and 
strip out the contents of the intestine. Then inject from the 
anterior end; this time the stream will go entirely through. 
Avoid too much pressure, as it will injure the tissues. Roll and 
knead the body while the stream is being started through. The 
fluid should be forced through the worm until it comes from the 
posterior end in a perfectly clear stream. The worm is then 
ready for fixing. 
ZoóLoGICAL LABORATORY, UNIVERSITY OF MICHIGAN, 
ANN ARBOR, MICH. 
1 Raymond Pearl. Fourn. of Applied Micr., vol. 3, no. t, p. 680. 
