STUDIES IN 'J'HE EXUEinMENTAU ANAl.YSIS OF SEX. 
273 
is found that although a very ricdi yield of orange-coloured 
lipochronie is obtained, yet the percentage in weight of these 
ether-soluble substances is very small, viz. about 1'5 per cent. 
Considering the intense coloration of the ethereal solution, 
it is certain that the greater part of this 1‘5 per cent, consists 
of lipochronie, so that there can be very little actual fat in the 
skin — a deduction which histological examination amply con- 
firms. 
^,Ve ma,y conclude, therefore, that fat is not used to any 
extent as a reserve material for the formation of the new 
skin, but that lipochronie is employed for the formation of 
the new skin pigment, and that the principal reserve material 
for the formation of fresh tissue is glycogen. We can, there- 
fore, readily explain the occurrence of the pink lipochronie in 
the blood of crabs soon about to moult, and the fact that this 
pink lipochronie is not accompanied to any great extent ivith 
fat, as is the case in the yellow blood of the female at the time 
of maturity. In her case there is a large mobilisation of fat and 
of lipochronie for the ovaries, but in the case of the moulting 
crab only lipochronie is required for the skin and not fat. 
Hitherto, in dealing with the lipochrome pigment found in 
the blood, liver and skin of the crab, we have merely called 
attention to the existence of two modifications of this pigment 
— tlie red, characteristic especially of the blood of males, and 
the yellow, characteristic especially of the blood of females 
maturing tlie ovary. It is convenient at this point to enter 
more fully into the nature and reactions of these two pig- 
ments, and to trace their functions in the organism. 
The most illuminating account of the two pigments has 
been given by Miss Newbigin (4) in her account of the 
pigments of the salmon, published in the ^Scottish Fishery 
Eeports.’ 
It appears that the two pigments, tlie red tetronerytlirin 
and the yellow lutein, which can be abstracted from the 
muscles and ovary of the salmon, are identical in their 
reactions with those found in the Crustacea, and that their 
behaviour in the organism is very similar in the two cases. 
