26 THE CELL DOCTRINE. 



clearly determined. As stages in its growing impor- 

 tance may be mentioned, the demonstration of the 

 cellular structure of plants by Kobert Hooke in 1667, 

 the further elaboration of this subject by Malpighi, 

 and his statement that each "utriculus" was an in- 

 dependent entity, the description of Heusinger, in 

 1822, of the mode of formation of vessels by the appo- 

 sition of vesicles, already referred to, and the announce- 

 ment, though erroneous, of Dolliuger, in 1828, that 

 the body is built up of blood corpuscles which move 

 in wall-less (wandlos) channels in the tissues. 



A most important contribution to the anatomy 

 of the cell was now made, in the discovery of the 

 " nucleus," by Dr. Robert Brown, of Edinburgh ; 

 whose paper, " Organs and Mode of Fecundation in 

 Orchidese and Asclepiadeee," appeared in the Trans- 

 actions of the Linnean Society of London, in 1833. 

 He failed, however, to appreciate its importance, 

 though its discovery was another fact added to those 

 necessary to complete the data on which has been 

 founded the so-called " cell theory." t 



Singularly near the truth did Raspail* approach, 

 in 1837, when he tells us that in the condition of 

 development there are vesicles or cells, endowed 

 with life and the property, almost unlimited, of pro- 

 ducing out of themselves other cells of the same 

 structure and similar endowments, of spherical form, 

 and capable of taking up oxygen when exposed to 

 the atmosphere; that the cell membrane in its fresh 

 state is structureless. Yet he considers the organic 



* Kaspail, op. citat. 



