508 ANIMAL NATURE OF DIATOMEiE. 



new individuals occurs, on the other hand, inside the 

 maternal cell of CMorococcus and Hamato coccus. 



The genus Grec/arina was proposed by Dufour, and 

 very well described by Siebold. Kolliker examined six 

 species {Die Lehre von der tJiierischen Zelle. Zeitschr. filr 

 wissenschaft. Botan. II Heft, p. 40.) They are sinaple 

 cells, containing very minute granules {granelli), small 

 drops of oil, and a central vesicle filled with a transparent 

 liquid, with a few oily drops, and a dark round nucleus. 

 They move by the expansion and contraction of the 

 cellular wall. Their reproduction is effected by an endo- 

 genous cell-formation. The contents separate into two 

 globular portions, which accumulate around two nuclear 

 vesicles newly produced; the membranes form round 

 the two globules, and thus arise two filial cells, which, 

 after the redissolution of the maternal cell, separate from 

 each other and begin to enjoy then- individual life. The 

 same author supposes that some species of Bodo, Monas, 

 Spirillum, Vibrio, &c., equally belong to this new family 

 of Unicellular Infusoria, but we have no direct observations 

 to prove this. 



Page 13. — Collecting together all that has hitherto 

 been observed as to the first origin of cells, the supposition 

 we are able to form is the following. The first elements 

 we are able to perceive are the so-called elementary 

 granules {granelli) in animals, and the mucous granules 

 in plants. These are very minute solid corpuscules, of a 

 quaternary azotised substance, capable of growth, but not 

 of multiplication, nor of ulterior development. In the 

 midst of these appear the nucleoli in plants. Around 

 every nucleolus, mucous granules collect together, forming 

 a species of crust. The body resulting from this is a 

 nucleus or cytoblast. Around this appears a membrane 

 of a quaternary azotised substance, which is the so-called 

 primordial utricle. Upon the external surface of this, 

 a membrane of ternary composition, not azotised, is 

 organised ; this is the true cell-wall, which alone remains 



