CORPUSCLES IN RED VASCULAR FLUID OF CHZTOPODS. 501] 
cerin. To guard against error it is important to see the 
corpuscles while actually within the walls of the vessels, 
and to move them up and down by gentle pressure on the 
coverslip to distinguish them from the nuclei of the cells of 
the wall of the vessel itself. This method is the one applied 
by Professor Lankester to the investigation of the red vas- 
cular fluid of the earth-worm, and it seems exceedingly pro- 
bable that in most Chetopoda when carefully applied, it 
will yield the same result as it did in that case, viz. evidence 
of the existence of corpuscles in the red vascular fluid. 
The corpuscles occur either singly or in small masses. In 
Eunice they are either round and average ;,),,th of an inch 
in diameter, or are oblong with a long diameter of 3,',;th 
of an inch. In Nereis the corpuscles are mostly round and 
rather smaller, varying from 79'5th to 4;4,;th of an inch in 
diameter. 
