36 



THE CELL DOCTRINE, 



Thecytoblasts then grow considerably in the free state, 

 C, but 80 soon as they have attained their full size, 

 a delicate transparent vesicle rises upon their surface, 

 assuming the relation of the watch-crystal to a 

 watch, D, E. This is the young cell, which at first 



Fig. 2. 



B o 



Cellular Tissue, from the embryo sac of Chamsedorea 

 Scbiedeana, in the act of formation. 



A, Formative substance, gum, mucus-granules, nu- 

 clei of oytoblasts (nucleoli). 



B, Cytoblasts. 



C, Single and free cytoblast, more highly magni- 

 fied. 



D, Cytoblast with cell forming in it. 



E, Same, more highly magnified. 



F, Cytoblast isolated after destruction of cell. 



From Schloiden's " BeitrSge zur Phytogenesis." 



represents a very flat segment of a sphere, the plane 

 side of which is formed by the cytoblast, and the 

 convex side by the young cell, which is placed upon 

 it somewhat like a watch-glass of a watch. In a 

 natural medium it is distinguished almost by this 

 circumstance alone, that the space between its con- 

 vexity and the cytoblast is perfectly clear and trans- 

 parent, and probably filled with a watery fluid, and 

 is bounded by the surrounding mucus-granules, which 

 have been aggregated at its first formation, and are 

 pressed back by its expansion, as shown in 1), E. But 

 if these young cells be isolated, the mucus-granules 

 may be almost entirely removed by shaking the 

 stage. They cannot, however, be absent for any 

 length of time, for in a few minutes they become 



