STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 251 
Studies in the Experimental Analysis of Sex. 
By 
Geoffrey Smith, M.A., 
Fellow of New College, Oxford. 
Part 7. — Sexual Changes in the Blood and Liver of 
Carcinus maenas. 
In the preceding parts of these studies evidence has been 
brought forward to show that the adult female organism at 
the time of the ripening of the ovary is engaged in elaborating 
reserve material, especially of a fatty nature, that this sub- 
stance is conveyed in the body-fluids to the ovaiy, and we 
have seen reason for associating the presence of this substance 
in the circulation with the development of many of the female 
secondary sexual characters. It w r as especially in connection 
with the effect of the parasite Sacculina upon its host 
Inachus that the probable importance of this process was 
recognised, and the hypothesis was advanced that the under- 
lying cause for the assumption of adult female characteristics 
by both sexes of infected crabs was the fact -that the 
Sacculina forced them to elaborate a fatty or yolk material 
similar to that which the normal female crab produces at the 
time that the ovary is ripening. Attention was called to the 
fact that the roots of the Sacculina actually do elaborate a 
yolk material from the blood of the host, similar in appearance 
and in staining reactions to the yolk which the adult female 
normally stores in its ovary. 
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