STUDIES IN THE EXPERIMENTAL ANALYSIS OP SEX. 51 
(4) The explanation of the fatty infiltration of the comb is 
found iu the fact that at the egg-laying periods the blood 
becomes charged with fatty material which is conveyed to 
the ovary for the formation of yolk, and that the excess of 
this fatty material is deposited in the comb. 
(5) A close parallel is observed in the fat metabolism of 
the laying hen and of spider-crabs parasitised by Sacculina. 
EXPLANATION OF PLATES 6-9, 
Illustrating Mr. Geoffrey Smith's “ Studies in the Experi- 
mental Analysis of Sex." 
Nos. 1-9 refer to young Bankiva liens, three months old at the 
beginning of the observations. 
Nos. 10-12 refer to adult Bankiva liens, two and a half years old. 
No. 13 refers to a white Leghorn hen, two and a half years old. 
The curves give the increase in area of the comb measured in square 
millimetres during a varying period of days. Tlie egg-laying periods 
are indicated by the vertical lines enclosed above in brackets. 
