1879. ] Destructive Nature of the Boring Sponge. 283 
ing spiculze of the ordinary form; these also may be perforate or 
imperforate and conical. Their office is not yet understood, but 
it is suggested by their discoverer that they are for the purpose 
of interrupting or modifying the direction and flow of the cur- 
rents of water created by the ciliated cells of the tissue lining the 
cavities of the organism. 
In the examination of a second specimen kindly handed me by 
Mr. Ford, and which had been removed from its native brine only 
a few hours before, I was enabled to distinguish very plainly the 
ova or gemmules strewn through the orange-colored sarcode. 
These are bodies fully three times as large in diameter as the 
ordinary sponge cell, of an oval shape covered with a tough 
transparent rather thick membrane. The contents are transpa- 
rent and granular with the exception of the nucleus, which is 
opaque and deep-orange in color and is often broken up into sev- 
eral apparently homogeneous granules of variable size; a part of 
these granules may occupy one extremity of the ovum, another 
part the other, or they may be placed eccentrically, or be arranged 
in a semicircle. The diversity in this respect is very great, so 
that but few are met with which are very nearly alike. These 
differences may represent various stages of development, but 
there seems to be a want of the orderly arrangement which 
would be expected if this were the case, besides, the wide sepa- 
-ration of the nuclear bodies into two and even three parcels 
would not favor such a view. 
I was quite unable to distinguish any flagellate cells in this 
specimen, even with a power of 1000 diameters, although there 
can be little doubt of their existence, as may be inferred from 
Prof. Leidy’s account of the physiological actions of the organ- 
ism. Mr. Carter, however, has figured these cells in a paper 
already referred to, and he observes that the flagelliform pro- 
cesses of the cells lining the canals of the fresh-water sponges are 
withdrawn into the sarcode body of the cell soon after being 
detached from the walls of the canals, which may have been the 
trouble in this case. 
