Poly gastric Infusoria. 1S7 



gest that the process of formation must be the same in both : the essen- 

 tial part of this process consisting in division of the pellucid nucleus. 

 And it is deserving of remark, that Ehrenberg describes his Monas bico- 

 lor evidently a nucleated cell, as possibly an early state of the Chlamy- 

 clomonas. 



" The curiously symmetrical forms of many of the Bacillaria appear 

 to be due to this two, four, eight, &c. division of the nuclei of cells. 



** The delineations of (Joniiim, Monis vivipara, and Ophnjclmm given 

 by the great naturalist just mentioned, afford most satisfactory examples 

 of a pellucid globule, dividing and subdividing like the hyaline in cells. 



" In many other of Ehrenberg's figures of the Polygastric Infusoria, 

 the corresponding part appears to me to be denoted by a blue, red, or 

 green colour, according as there had been added either indigo, carmine, 

 or sap-green. This accords with what has been mentioned in a former 

 page, regarding cells, namely, that a foreign substance becomes added 

 and assimilated through the hyaline. 



" Fecundation of the ovum takes place in the same manner as nutri- 

 tion of the cell, and seems, in some instances at least, comparable to the 

 nutrition of one of the Infusoria. 



" But farther, I recognise in Ehrenberg's delineations of the Infusoria, 

 not merely a cell-formation, but everywhere the existence of transitory 

 or assimilative cells. 



'* And farther still : the infusorial cells, like the cells of the larger or- 

 ganisms, have their origin in globules which become discs or ' cyto- 

 blasts ;' these passing through stages such as those of ordinary cells. 

 Thus in Ehrenberg's Monadina are to be found, I think, the following 

 grades, perfectly analogous to the grades of cells : — 



"1. Globules and discs. 



" 2. Discs with a pellucid point. 



" 3. The point dividing. 



" 4. Nucleated cells. 



'* 5. The nuclei dividing and thus giving origin to 



" 6. Young cells, which are seen both within and escaped from pa- 

 rent cells. 



*' There really seems to have been much truth in the remark long 

 since made by Oken, that animals are groups of bodies comparable to 

 the Infusoria. The cell is itself a little organism ; and cells coalesce to 

 form a larger one. 



*' The remarks just made respecting fissiparous generation, I appre- 

 hend, may be applied to gemmiparous reproduction, or propagation by 

 means of buds." 



No doubt the minute Infusoria, which seem to have their development 

 arrested at the first or nearest stage from the primitive cell-formation, 

 offer close and striking analogies to the primitive cells out of which the 

 higher animals and all their tissues arc developed ; but the very step 

 which the Infusoria take beyond the primitive cell-stage invests them 



