306 LANGENBECK. [VoL. XIV. 
normal way; but the eggs, although apparently quite normal, 
evidently were not fertilized, because they did not segment. 
I concluded, therefore, that in Microdeutopus, as in the other 
amphipod, fertilization takes place between the time of slough- 
ing and the time of extrusion of the eggs. It was also ob- 
served that when a moulted amphipod shell was found floating 
at the surface of the water a female which had lately extruded 
her eggs was almost always in the dish. 
When the eggs are first extruded into the brood pouch they 
are of a bright opaque green. The chorion closely invests the 
egg, but no other membrane could be seen either in the fresh 
specimen or in the sections. The eggs seem to be covered 
with some sticky substance, which causes those coming from a 
single ovary to cling to one another; but the groups of eggs 
from the two ovaries are separate. This substance is subse- 
quently either absorbed or loses its sticky properties, because 
after the first cleavage the eggs separate readily as soon as they 
are removed from the brood pouch. The protoplasm is found at 
the center of the egg. It is irregular in outline, sending out long 
pseudopodia-like prolongations, which ramify throughout the 
egg, very much as Dr. McMurrich ('93) has shown to be the 
case in the egg of Jaera. No protoplasmic layer could be seen 
around the periphery of the egg, however; if it is there, it must 
be very thin. Fig. 19, which represents an egg passing from 
the 2-cell into the 4-cell stage, shows the manner in which the 
protoplasm ramifies throughout the yolk mass. The nucleus 
is found in the center of the protoplasmic area. 
The segmentation in the early stages is total, but not equal; 
later it is superficial. The protoplasm loses its control over 
the inner ends of the blastomeres as it moves nearer the sur- 
face in the succeeding divisions, and the inner ends of the 
blastomeres fuse, so that the blastocoel, which is at first 
present, is obliterated. 
2-cell stage. — About three hours after the eggs have been 
extruded into the brood pouch, the protoplasm in the center of 
the egg divides, the nuclear spindle lying in the long axis. 
After the two halves of the central protoplasm have separated 
a furrow appears at the surface of the egg and gradually deepens, 
