216 
LlEBERKiiHN, ON SPONGILL^. 
become developed. He has never seen sponge-cells produced 
from them in the way described by Mr. Carter^ and asserts 
that the process of development is entirely different from 
that stated by that observer. The first change in the gem- 
mules was noticed in March. The cells no longer liquefied 
as before in the water when expressed from the gemmule, 
and exhibited amseba-like motions like the common sponge- 
cells. In many of the cells two nuclei with nucleoli might 
be observed, and, upon the whole, the larger vesicles did not 
contain so many cells, and presented a greater proportion 
of finer granules. 
He placed a number of these gemmules in watch-glasses, 
and exposed them to the sun for some time every day. In a 
few days a fine white deposit might be seen surrounding 
some of the gemmules, which was found, under the micro- 
scope, to be composed of an agglomeration of coherent 
sponge-cells, which was still in connection with the contents 
of the gemmule through its pore. This substance was firmly 
adherent to the bottom of the glass. In other gemmules 
the extracted cellular substance was situated, not on the side 
next the glass, but upon the upper side, — in fact, wherever 
the pore was placed. The escape of the cellular substance 
was very slow, so that the case was not completely emptied 
under four days. The development of the sponge, therefore, 
would seem to take place by the escape of the contents of 
the gemmule through the pore. The external surface of 
the cellular mass thus protruded gradually becomes trans- 
parent, no longer exhibiting the large vesicular structure it 
before possessed, and presenting instead the minute granules 
characteristic of the common sponge-cells. Conical per- 
forated eminences afterwards make their appearance upon 
this nascent sponge -sub stance. The same process takes place 
in the gemmules which have been retained within the horny 
skeleton of the sponge ; but in this case the cellular substance 
produced from each gemmule coalesces with that from the 
contiguous gemmules, and the whole forms a continuous 
mass, which necessarily assumes very much the form of the 
original sponge, owing to the circumstance that it is deposited 
upon the old skeleton. 
The commencement of the formation of spicules was 
observed by Lieberkiihn about the sixth day after the expul- 
sion of the contents of the gemmules. On breaking up the 
cellular substance, extremely delicate needles might be ob- 
served, some of which were smooth, whilst others presented 
a rounded swelling in the middle. The further development 
of these spicules will be noticed below. 
