ANIMAL NATURE OF DIATOME^E. 365 



Whilst unable to confirm or refute the opinions of 

 Ehrenberg, we seem to have observed facts sufficient to 

 disprove those of Kiitzing. First, besides the three sub- 

 stances or bodies of a different nature described by this 

 author (the gonimic matter, the oil globules, and the 

 presumed stomachs of Ehrenberg), we observe in all 

 species when examined alive, and in many after death, a 

 colourless substance, mostly extended in the form of a 

 membrane, and which seems to stand in continuity with 

 the remaining contents. Indeed Corda observed and 

 figured it, and Ehrenberg, as well as Kiitzing himself, 

 makes frequent mention of it in his descriptions. I 

 dare not assert anything as to the nature and functions 

 of this fine membrane ; but I do assert, notwithstanding, 

 that in its appearance, in its form, and its behaviour 

 under the action of chemical reagents, it differs from the 

 thin membrane or primordial utricle of the vegetable 

 cell, to which it might be compared. 



With respect to the so-called gonimic substance, its 

 identity with the endochrome of the Algae is not at all 

 proved. Its colour is different, and it is differently 

 coloured by chemical reagents. The resemblance to it in 

 some instances, as in Melosira, in regard to conforma- 

 tion and successive alterations, is only in appearance. In 

 the endochrome of Algae the monogonimic substance 

 begins by presenting a granular appearance, then it be- 

 comes distinctly granulated, and changes into the poly- 

 gonimic substance so minutely described by Kiitzing. 

 But these changes do not occur in the coloured substance 

 of Diatomeae. If we insist upon a parallel, we can only 

 compare it to the cryptogonomic (crittogonomicd) sub- 

 stance of Byssoidia, Callithamnia, Griffithsia, and Poly- 

 siphonifB. It divides into parts, which successively un- 

 dergo ulterior division. And in regard to these changes, 

 we may observe that there is an essential distinction 

 between those that occur during life and those that take 

 place after death, the greater number happening in the 

 latter condition. And, during life, besides the changes 



