54 THE CELL DOCTRINE. 



(as in Hydrodictyon, Vaucheria, Caulerpa, Sphag- 

 num), it is indubitably absent; and since he did not 

 include the nitrogenous primordial utricle, discov- 

 ered by Mohl, in 1844,* as one of the elements of 

 the cell. 



Finally, Schwann's mode of cell-development is 

 erroneous, having " been long since set aside by the 

 common consent of all observers;" cell-development 

 always occurring by division, except in the embryo 

 sac of the Phanerogamia, the sporangia of Lichens, 

 and of some Algse and Fungi ; and even the free 

 cell-development of the latter is quite different from 

 that of Schleiden and Schwann, being by the devel- 

 opment of a cellulose membrane (periplast) around 

 a mass of nitrogenous substance (endoplast), which 

 may or may not contain a nucleus. 



The difference between the views of Schwann and 

 Huxley are best expressed by the latter in the con- 

 trast he draws between those of Schwann and Wolf: 

 "For Schwann, the organism is a beehive, its action 

 and forces resulting from the separate but harmoni- 

 ous action of all its parts. For Wolff (and Huxley), 

 it is a mosaie, every portion of which expresses only 

 the conditions under which the formative power 

 acted, and the tendencies by which it was guided." 



The statements of Prof. Huxley with regard to 

 cell-development entirely accord with the most recent 

 observations on the subject, and are quite important 

 to us in tracing out the present state of the cell doc- 

 trine. 



* The existence of the primordial utricle is denied by many 

 botanists of the present day. 



