THE CELL DOCTRINE. 39 



" whatever cavillers may say, it is certain that histol- 

 ogy before 1838, and histology since then, are two 

 different sciences in scope, in purpose, and in dig- 

 nity and the eminent men to whom we allude, 

 may safely answer all detraction by a proud i circum- 

 sp-ice.' "* 



According to these observers, then, a perfectly- 

 formed cell would be defined as a dosed vesicle, with 

 certain contents, among which were essentially a nu- 

 cleolus and nucleus. 



HENLE, 1841. 



It is not consistent with our object to include all 

 of the numerous observations which were multiplied 

 after this period, incited by the researches of Schlei- 

 den and Schwann. It is simply to point out the 

 salient features of those results which point towards, 

 and have culminated in accepted views. It has 

 been stated that previous to Schleiden's researches, 

 in 1838, the formation of cells by division had been 

 asserted as one mode of origin of cells, that Schlei- 

 den had declared this an error of observation, and 

 that Schwann had hesitatingly, if at all, accepted it 

 as a rare method of cell formation. 



Henle,f who, in general, adopted the view of 

 Schwann as to the primary origin of cells, though he 

 made exception to its universality of application, 

 says that cells multiply in three ways : 



1. By budding (durch Sprossen), as in certain lower 

 plants. 



* Huxley, op. cit., p. 290. 



f Henle, Allgemeine Anatomie. Leipzig : 1841, p. 172 et seq. 



