STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 257 
extract. It is clear, therefore, that the pink lipochrome 
represents a very small proportion by weight of the fatty 
material extracted from the blood, and that for its weight 
it has a disproportionately great power of colouring the 
blood. 
It is also interesting to observe that the presence in small 
quantities of the yellow lipochrome can always be detected in 
the extract obtained from what was apparently quite colour- 
less blood. It is, in fact, impossible, as far as my experience 
goes, to obtain blood, however colourless, that does not yield a 
small quantity of the yellow lipochrome. This substance is 
therefore always present in the blood of both males and 
females, though the amount of it varies so greatly at different 
phases of the crab’s life, and is enormously increased in the 
female at the time of the ripening of the ovary. 
The difference that we have established between the two 
sexes in the properties of their blood is therefore a quantita- 
tive one, and though qualitative differences may lie behind 
we have no evidence as yet for their existence. It will, 
however, be perceived that the results of these estimations 
have resolved our difficulty with regard to the presence of the 
lipochrome in the male’s blood, since we have shown that 
the presence of this pink lipochrome in the male indicates a 
lower fat pontent than the yellow lipochrome of the female. 
Some observations may be conveniently made here as to 
the fate of these lipochromes and their associated fatty 
materials, and their probable function in the organism. In 
the case of the female we know that the yellow lipochrome is 
taken up by the ovary, which progressively becomes bright 
yellow as it reaches maturity, while the lipochrome 
coiucidently disappears from the blood. A certain amount of 
the pink lipochrome also finds its way into the ovary, but it 
represents an unimportant amount of the reserve material as 
compared with the yellow. But there is another destination 
for the pigments, the sole destination for them in the case of 
the male, and that is the integument. As the males and 
females pass from the soft green-coloured condition 
