284 
GEOFFKEY S^HTH. 
is the steady drop in glycogen content after 48 hours’ starva- 
tion. This indicates that the infected crabs have not any 
accessory stores of glycogen in the body to draw upon, so 
tliat after a certain period of starvation the liver glycogen is 
called upon to supply the material for carrying on the ordinary 
metabolic processes of the body, and is consequently soon, 
nearly exhausted. We have already seen that Carcinus 
infected with Sacculina does not possess stores of glycogen 
in the skin to anything like the same extent as normal crabs,, 
so that we can easily understand this drainage of glycogen 
from the liver in the case of infected crabs which does not 
occur in the case of normal crabs. In the latter it is probable 
that during starvation the skin glycogen is transferred from 
the skin to the liver and used for ordinary metabolism — a 
supposition which is amply confirmed by the fact that starved 
or underfed crabs never moult in an aquarium however near 
they may be to the moult when captured. 
The quantitative results on glycogen-content of the livers 
of normal and infected crabs fit in, therefore, very well with 
the other observations as to the lack of glycogen in the skin 
of infected crabs and their incapacity to moult. 
Turning to the fat percentages, we remark the same 
variability in the normal crabs as in the case of the glycogen- 
content. The effect of starvation up to 532 hours appears to 
be negligible, since there is no regular diminution in fat- 
content to be observed as the starvation is prolonged, but 
from 24 to 532 hours’ starvation the variation in fat-content 
runs from 5'65 per cent, to 13*53 per cent. 
Comparing this with the fat-content of infected crabs, as 
exhibited in the fifth column of the table, we see, firstly, that 
the variability is not so great, and, secondly, that the averuge 
percentage in the case of the infected crabs is a good deal 
higher than in the normal males. It is true that in certain 
cases the normal males show a fairly high percentage of fat,, 
e. g. 13‘53 per cent., but it has never been claimed that in 
every case infected crabs have a higher percentage than the 
normal. What is claimed is that on the average the infected. 
