Vascular and Nervous Systems. — The heart and blood-vessels 
are not affected to any marked extent by the change. They become 
slightly more transparent and flabby, the muscular fibres appearing 
to be somewhat relaxed. The function of the heart being 
continuous, we might expect that it necessarily must escape the 
stagnation produced in the other organs. How can this be 
managed ? The solution appears to lie in the question of the 
effect of pressure on tissues and organs. Undue pressure has a 
degenerating effect on organs as a rule, in some cases even causing 
a certain amount of atrophy. The organs of the crab, growing 
constantly in the periods between ecdyses must exert great 
pressure upon one another, as is evidenced by the great expansion 
immediately after casting. The organs under this pressure must, 
therefore, he somewhat affected in their development. But the 
heart, lying as it does in its pericardial sac, will be able to 
expand in a natural manner as it develops, and may thus 
probably escape the pressure experienced by the other organs. 
Much the same thing may apply to the nervous centres, which 
seemed little affected. The nerves, however, were less opaque 
and more difficult to follow. 
The Liver. — The liver is very large in the crab and occupies a 
large part of the thorax. It is thus very liable to modification by 
pressure previous to casting. The effect, however, is not so great 
owing to the fact that at this period the reproductive organs which 
lie upon it are in an unripe condition, and, consequently, allow a 
counterbalancing space for expansion. That the liver has increased 
in size is very evident. The fat cells which have an absorbing 
function are well stocked with matter of an excretory nature, 
as well as glycogenous reserve material. The larger type of 
fermenting cells, too, are distended. The vacuoles containing 
the drops of brown digestive juice are enlarged, and this excess of 
liquid gives the liver a browner appearance in the soft stage. The 
most interesting point about the liver of the soft crab is the 
presence of glycogen in the excretory fat cells (Cuenoff). 
The Reproductive Okgans. — The changes seen in the 
reproductive organs are very 'striking. In the female, as stated 
above, it is only when quite soft that impregnation can tale 
place. The vaginae are never plugged when the crab is about 
to cast. Consequently, the shedding of the chitinous wall of 
the vaginae and spermathecae is easily performed. Immediately 
after this slough, the glands of the spermathecae secrete a fluid 
