48 
be drawn through the small apertures at the base, though the f 
process is probably assisted by the presence of decalcified patches of > 
the cuticle in these regions. After the blood returns to its normal 
state the myosin will again be laid down. The only change worth J 
mentioning in connection with the involuntary fibres is that an 
excess of nuclei points to cell division. 
In the nervous tissue little change has been noted. 
The tubules of the digestive glands in the hard condition u 
present a fairly spacious lumen, and the epithelial cells are con- | 
stantly throwing off fragments containing secretory and excretory i 
material. In the soft condition the cells are vacuolated, some 
containing fat, and the tubules are filled with numerous cells wliich 
appear to have arisen from the epithelial layer, and which take on ' 
the function of reserve cells. 
The condition of the reproductive organs has not received 
further attention. Suffice it to remark that they are immature in 
both sexes in the soft condition.- The testes show germ cells in 
their lobules, but no sign of spermatogenesis. In the female the 
ovisacs are not developed from thh germ cells. But development 
in each case, that is after maturity has been reached, of the several 
elements from the primary germ cells begins soon after ecdysis. 
The main-' points brought out in the above observations are the 
facts that ecdysis is a period of new birth to the tissues, that so far 
as the somatic tissues are concerned there succeeds on the renewal 
of the shell a period of rapid growth which gradually ceases with 
the calcification of the shell, and that it is probable therefore that 
the active cause of the ecdysis is not that the growth of the tissues 
has brought about a state of physiological embarrassment which 
the casting of the shell would remove, but that the cause is the 
introduction of a large quantity of sea water which going to increase 
the volume of the blood, gives the requisite internal pressure for 
carrying out the process. What, however, is the impulse which 
prepares the way for the change is at present not at all clear. 
