Mr. H. J. Carter on Difflugia pyriformis. 259 



Nitella, the spherules become the new brood, and, on leaving 

 the nucleus, pass into the ejffete cell of the parent, where still 

 remain the contents (starch and chlorophyll) originally incepted 

 by it in the internodal cell of its host ; after feeding on which 

 (for portions of it may be seen in their bodies), these mono- and 

 diplo-ciliated monads (individuals of the new generation) find 

 their way out through the effete parent-cell, and commence their 

 independent existence. 



It is thus, in all probability, that the granuliferous cells in 

 Difflugia pyriformis leave the nucleus, multiply rapidly by du- 

 plicative division (for their number in the body of the parent far 

 exceeds that of the number of the spherules of the nucleus), 

 feed on the starch laid up for them, and finally, becoming ciliated, 

 leave the effete parent, to obtain their future maintenance and 

 development. 



The granulation of the nucleus in Difflugia, as before stated, 

 seems to be the same as that which I have described in Amoeba 

 princeps ; but that of generation by the " reproductive cells " in 

 A. prnnceps is altogether a different process. In the former, 

 several centres of new individuals become developed in the pro- 

 toplasm of the nucleus, while in the latter the nucleus appears 

 to begin to form the " reproductive cells '^ by dividing at once 

 into two equal portions, and so on. But both processes, in 

 their generative imports respectively, are as yet very imperfectly 

 understood ; and at present we know no more of them, as regards 

 impregnation, than we do of that of the conjugating Confervoid 

 Algse generally, the Diatomacese or the Desmidiacese. 



Observations. — In the starch-granules of Difflugia pyriformis 

 I cannot help seeing the refractive "cells" (or, rather, granules), 

 with the small granules and protoplasm, which fill the globular 

 cells of the seed-like body of Spongilla, each of which globular 

 cells, in the early stage of this body, is a bond fide Amoeba ; and 

 when the new sponge-substance issues from the hilous aperture 

 (that is, when the seed-like body germinates), each of the glo- 

 bular cells (now become effete), with its contents, appears to 

 pass into one of the " ampullaceous sacs^^ (see a description of 

 this, " Ultimate Structure of Spongilla," ' Annals,' vol. xx. p. 21, 

 1857), while the refractive cells or granules gradually disappear, 

 and are replaced by the polymorphic cells which chiefly enter 

 into the composition of this "sac." Thus my original view, 

 that these refractive grains are "ovules," is changed, as an- 

 nounced in 1859, in my observations " On the Identity in Struc- 

 ture and Composition of the Seed-like Body of Spongilla with 

 the Winter-egg of the Bryozoa, &c." (Annals, vol. iii. p. 331), 

 where I have also stated, for reasons therein mentioned, that 

 these refractive granules appear to pass into the formation of 



