150 THE CELL DOCTRINE. 



the higher forms of animal and vegetable life the 

 only method of cell genesis which is constantly before 

 us, while the phenomena of spontaneous generation 

 are confined to the creation of the lowest vegetable 

 and animal organisms, so that the proposition omnis 

 cellula e celluld may be now considered as generally 

 accepted. Prof. H. Charlton Bastian remains the 

 most eminent English supporter of the doctrine of 

 spontaneous generation, against whom Huxley, Rob- 

 erts, Tyndall, Beale and others have directed arti- 

 cles and experiments. 



In the division of cells to produce young cells, it 

 is usually in the nucleus that the segmentation first 

 begins, extending thence to the protoplasm outside of 

 it, although this is not invariable. For any portion 

 of the bioplasm of a cell may grow, separate and form 

 a young cell. It is the bioplasm or germinal matter 

 alone, however, which can give rise to the cell, and 

 never the non-germinal matter or formed material. 

 It is seldom, also, that we see in the animal cell, ex- 

 cept in the segmentation of the fecundated ovum, 

 that symmetrical division of the nucleus into two, 

 these into four, these into eight, and so on, as is con- 

 stantly seen in the vegetable cell, but it is rather a 

 budding»and subsequent dropping off of portions of 

 bioplasm which become young cells, and which al- 

 most always assume the spherical form when allowed 

 to float .freely (see Fig. 10, of frontispiece). 



Strasiburger,* in his recent work on Cell Formation 

 and Cell Division, admits three methods of increase 



* Ueber Zellbildung und Zelltheilung, Jena, 1876. 



