1286 
GEOFFREY SMITH. 
frequently than the male, and yet only attains to about half 
his size. It is fairly ceiTain that the large quantit}" of glycogen 
stored in the liver and skin of Crustacea before the moult is 
not only used for forming the new skin, but also for the 
repair and growth of other tissues, so that it is quite possible 
that the male Amphipod mentioned above really stores more 
glycogen than the female, although the latter moults more 
frequently. The anomaly of the hermit crabs moulting with- 
out active growth, under the influence of Peltogaster, may 
therefore be due, not to an increased glycogen storage, but 
to some other stimulus leading to frequent moults, despite the 
comparative depression of the glycogenic function. If it 
could be shown that hermit-crabs parasitised by Peltogaster 
actually exhibit a comparative poverty of glycogen in liver 
and skin, despite their frequent moulting, a complete agree- 
ment might be shown to exist between this case and that of 
Carcinus in respect to the glycogenic functions. 
In connection with these observations it is of interest to 
note that in normal Carcinus the adult females never attain 
to anything* like the same size as the adult males, though they 
presumably moult as frequently. It is highly probable, there- 
fore, that normal adult females, as the result of their breeding 
activities, lack a plentiful supply of glycogen for the purpose 
of growth, and if this is the case we are presented with another 
similarity between the metabolism of normal females and in- 
fected individuals, viz. the depression of the glycogenic func- 
tion. 
4. Summary of the Physiological Action of Sacculina on 
ITS Host. 
The analysis of the morphological changes brought about 
by Sacculina and Peltogaster on their hosts may be shortly 
summarised in the statement that these parasites act through- 
out as feminising agents, converting* the male externally and 
interncF.Uy, in various degrees, to the female state, and leaving 
the female either unchanged or else hastening on the adult 
