and the Winter-egg of the Bryozoa. 339 



the refractive granules of the ovum of Spongilla is only another 

 form of aliment instead of starchy which, under the vitali- catalytic 

 influence of a thin film of protoplasm, passes into a like material 

 endowed with a specific form and peculiar properties. Such, en 

 passant (for this is not the place to go deeply into the subject), 

 is the theoretical view that I am now inclined to take of the 

 import of these refractive granules in development, viz. that 

 they become assimilated by amoebous films of protoplasm spread- 

 ing over them, and thus pass into the monociliated and un- 

 ciliated proteiform cells. 



The fact of the monociliated and unciliated cells being pro- 

 duced from the contents of the ovum of Spongilla when they 

 are forcibly ejected as well as when they issuo in the natural way 

 (that is, under development), is also corroborative of the view 

 that not only the polymorphic contents of the cells of the Algse, 

 but (as I have shown) those also of the e^^ of Nais^, do take 

 on these forms of themselves under certain circumstances — when 

 the specific figurating power which held the protoplasm together 

 in its proper course appears to be arrested, and not from the 

 presence of the germs of any foreign organism, as some of 

 the German algologists affirm, from which I am glad to find 

 Prof. Henfrey at least withholding his concurrence f. The 

 moving protoplasm of the internode of Nitella is chiefly com- 

 posed of delicate polymorphic cells, which, the moment the 

 green layer is broken up by a transverse section of the tube, 

 seize and enclose some of the cells of this layer as the whole of 

 the contents are issuing together into the water ; and it is when 

 the green discoid cells are in the protoplasm of the interior of 

 the polymorphic cells that they sometimes exhibit the rapid 

 rotatory motion first noticed by Donne {, and which appears to 

 be produced by this protoplasm. Thus it is that under other 

 circumstances, when the green layer is broken down or gives 

 way under the entirety of the cell-wall of the internode, the 

 polymorphic cells of the moving protoplasm fill themselves with 

 the cells of the green layer, which, generally containing a large 

 amount of starch, thus afibrd material for assimilation into the 

 protoplasm that ultimately becomes divided up into a litter of 

 polymorphic monociliated monads, which also, in accordance 

 with the views of the German algologists to whom I have alluded 

 (for it is only a favourable instance for examination of what 

 under certain circumstances takes place in the cells of all the 

 freshwater Algae, so far as my observation extends), should be 

 regarded as the progeny of a foreign organism. To me there ,, 



* Annals, vol. ii. pi. 4. fig. 45, 1868. 



t Quart. Journ. Microscop. Sc. No. 2Q, p. 27, 1859. 



:|; Annals, vol. xvii. p. 107, 1856. 



22* 



