494 FOOT. [VoL. XIV. 
of the polar-bodies, the egg turns slightly at indefinite inter- 
vals. These movements are not oscillatory, as sometimes 
three consecutive turns will occur in the same direction, 
revolving the egg one quarter its diameter. Later they appear 
to change the relative position of the egg and first polar-body, 
thus removing the first polar-body from the path of the second. 
Pathological changes in the egg, which are induced sooner 
or later by the artificial examination medium, seem to appear 
first in the cytoplasm. An egg studied during the formation 
of the second polar-body (60 minutes) and for three hours 
thereafter, showed marked pathological changes in the cyto- 
plasm. The polar rings did not develop, and the cytoplasm 
finally appeared as a mass of large vacuoles. During the 
period of these changes in the cytoplasm, the pronuclei con- 
tinued to develop ; for after killing, staining, and mounting 
the egg, the pronuclei were found to have reached their maxi- 
mum size, and were in contact in the center of the egg, neither 
showing pathological features. The cytoplasm, however, 
showed the same pathological condition seen in the living egg. 
As I am at work on a paper which will give the results of a 
comparative study of the living and fixed cytoplasm in these 
eggs, I shall omit here any description of the living, normal 
cytoplasm. 
A large number of living eggs have been measured with a 
view to testing the shrinkage or swelling produced by various 
fixatives. The living odcytes, Ist order, have varied in size 
from 100p to 132m, the odcytes, 2d order, from 114m to 140p, 
the ripeegg from 128 to 144, the pronuclear stages from 
1364 to 152. These figures differ slightly from those given 
in my preliminary note (5), owing to the fact that the measure- 
ments were taken from fixed material. The eggs are not 
spherical at all stages; but these details will be illustrated 
later in a series of photomicrographs. 
Spermatozoa. — Free spermatozoa can be procured by 
removing the slime-tube from copulating worms, drawing out 
part of its contents with a fine pipette, and drying on slides a 
thin layer of the seminal fluid thus obtained. They can be 
procured from a freshly deposited cocoon by drying on slides 
