Mr. H. J. Carter on Spongilla. 367 
I have used the term “microcell-structure” (cbid. p. 
83, pl. v. fig. 2). In Parmula Brownii, however, it 1s 
much larger than in P. Batesii, and thus can be well seen 
under a power of 300 diameters, when it is found to be com- 
posed of spherical cells of different sizes, heaped together with 
the utmost irregularity (Pl. XVI. fig. 12) ; so that in structure 
and composition, although not in form and arrangement, it 
differs markedly from the uniform size and hexagonal figure 
of the cells in S. Cartert and S. nitens. 
Lately another instance of the latter kind has been brought 
to my notice by Mr. Ed. Potts, of Philadelphia, in a species 
allied to Spongilla fragilis, Leidy (‘= 8S. Lordit, Bk.’), var. se- 
gregata, Potts. This Spongilla, which is found at “ Chester 
Creek ’’ and other places im the State of Pennsylvania, is 
remarkable for having its statoblasts developed in fours, so as 
to present the tetrahedral form of the sporangium in Selagi- 
nella cernua &e. (Pl. XVI. fig. 9), surrounded in like manner 
by a capsule or layer composed of hexagonal cells like those 
ot S. Cartert &c. (figs. 9, ddd, and 11, a, 6), arranged in a 
columnar form throughout, but most evident in the angles 
between the statoblastlets, because it is thickest there, since 
it fills all the intervals between the four statoblastlets, thus 
causing the whole to assume a globular, tetrahedral shape. 
As this species will be more particularly described by Mr. 
Potts hereafter, the only part that concerns us now is this 
vegetable-looking cell-structure ; and although, as I have be- 
fore stated, starch-granules are mixed up with the germinal 
contents of the statoblasts, as in most seeds, yet the polygonal 
cell-structure of the capsule, when tested for cellulose in the 
usual way with sulphuric acid and iodine, presents nothing but 
a light amber colour, identical with that of the pith of Elder 
(Sambucus nigra) under the same circumstances; so that, 
although the blue colour of starch may not be produced in 
the polygonal cell-structure of Spongilla, it does not follow 
that it is’a bit less composed of cellulose than Elder. 
If we turn to the marine sponges for an instance similar 
to this parenchymatous tissue of Spongilla, I know not where 
to find it, unless the core or pith in the Ceratina be of this 
nature (see ‘ Annals,’ 1881, vol. vii. p. 115, pl. ix. fig. 11, /). 
The “granules”? here, which I have conjectured to be 
* cellule in embryo,” form a light substance of a whitish-grey 
colour, very like the “ microcell-structure ” to which I have 
above alluded (Pl. XVI. fig. 12). 
With reference to the “ green colour” in Spongilla, I can 
state no more than I did in 1849, which is thus recapitu- 
lated :—“ It is impossible, therefore, under these circumstances 
