PROCESS OF FERTILIZATION IN THE CRAB 179 
Finally, if we may accept the views of Stauffacher (10) and 
Derschau (’11), that basichromatin is derived from oxychromatin, 
the former being deposited from the latter, we may postulate a 
theory for the explanation of the phenomena of fertilization in 
this crab. I do not claim that the facts establish the theory; 
they only suggest it. Some of the basichromatin in the nucleus 
of the spermatid is dissolved by the oxychromatin and trans- 
ferred to the capsule. After the capsule is everted into the egg 
and has entered the cytoplasm of the latter, the basichromatin 
is redeposited and thus the granular structure of the male pro- 
nucleus appears. It may be possible to explain the number of 
chromosomes which appear, by supposing that there are a cer- 
tain number of different kinds of molecules which are deposited 
out of the oxychromatin and that these have such an affinity 
for each other that they are aggreagted into a definite number 
of groups, or they may be of such a structural nature than they 
ean fall only into certain groups. Of course, I claim for this 
only that it is a possible explanation of phenomena which are 
apparently not in accord with the conception of an individual 
continuity of the chromosomes. 
10. SUMMARY 
1. The seminal elements in Menippe mercenaria arise from a 
single row of primary spermatagonial cells which persist along 
one side of the testicular tubule. 
2. The tubule is divided into three or four regions by longi- 
tudinal partitions composed of epithelial cells. The seminal 
elements in the division next to the row of primary sperma- 
togonial cells are younger than those in any other division. 
The region on the opposite side contains mature spermatozoa. 
The seminal elements in one end of a given division are further 
along in their development than those in the other end. 
3. The spermatogonial nuclei lie in a common cytoplasmic 
mass and multiply irregularly without the formation of a spireme. 
JOURNAL OF MORPHOLOGY, VOL. 24, NO. 2 
