EFFECT OF SACCUL1NA UPON FAT METABOLISM OF HOST. 271 
ovary of the mature female a marked increase in the blood- 
lipochrome — in this case yellow. 
I think it possible from the above data, taken in conjunction 
with our knowledge of the habits and development of these 
animals, to formulate the following explanation. 
Fat is indicated in the blood of the male and female both 
in the normal and infected conditions, but it is signally 
increased at the period of rapid moulting, in the breeding 
season, and in the sacculinised condition in both sexes. These 
three phenomena are, then, comparable in their effects on the 
fat-metabolism of the crab. But of these three, as far as 
numerical proportion goes, the state of the breeding female 
and that of the infected animals of both sexes seem to be 
more closely akin, and to represent a development of fat more 
constant or more intense than in the moulting animals. I 
think it is a legitimate deduction to suggest that the action 
of the Sacculina closely resembles the function of the ovary, 
namely, to collect a nutritive substance circulating in the 
blood. I do not propose to attribute to this increase of fatty 
material any mysterious and ill-defined power of “ conditioning 
the formation ” of the secondary sexual characters, though I 
admit the propriety of such speculation. All I propose to 
sny at present is, that the constancy of a fatty substance as a 
property of the blood of sacculinised auimals is yet another 
expression of the profound physiological disturbance set up 
in the infected crab, a disturbance which always seems to end 
by metamorphosing the male and the immature female into 
a condition corresponding to that of female sexual maturity. 
Thus far we have dealt with the blood alone and have 
based certain conclusions thereupon. It will now be con- 
venient to show that the effects of moulting, the period of 
female sexual maturity and sacculinisation are similarly 
registered upon the liver , 1 regarded in the light of its 
function as a fat-storing organ. 
1 I use the term “ liver” merely for the sake of convenience, though 
readers may substitute “ hepato-pancreas ” or “gastric gland” accord- 
ing to their views. 
