X vn MYSTERY OF THE CELL 345 



nucleus a partition wall of cellulose is interposed in the gap, and 

 from a single cell we have now produced a pair of cells " (vol. i. 

 p. 48). 



But later on we have a much fuller description, illustrated 

 by four diagrammatic figures of the dividing cell, which show 

 that the process in plants is substantially identical with that 

 described and figured already from Weismann (vol. i. p. 581). 

 This is most instructive, because it shows the absolute identity 

 of the fundamental mechanics of life in the animal and vege- 

 table kingdoms, though their ultimate developments are so 

 wonderfully diverse. 



Another interesting point is that, just as Weismann has 

 stated, there is an identity in the number of certain elements 

 in the cell for each species. Kerner's statement is : 



" For every species of plant the number, size, and shape of the 

 bodies arising in the interior of a cell by division are quite definite, 

 though they vary from species to species. In the cell-chambers of 

 some species several thousand minute protoplasmic bodies arise. 

 In others, again, the number is very limited. If the number is 

 large the individual masses are exceedingly small, and can only be 

 recognised when very greatly magnified. If the number is limited 

 the divided portions are comparatively large. The shape of the 

 structures is exceedingly various. Some are spherical, elliptical, or 

 pear-shaped ; others elongated, fusiform, filamentous, or spatulate ; 

 some are straight, others are spirally twisted, and many are drawn 

 out into a thread ; others are provided over the whole surface with 

 short cilia ; others, again, with a crown of cilia at a particular spot, or 

 with only a single pair of long cilia. In the majority of cases the 

 small bodies exhibit active movements ; but sooner or later they 

 come to rest, and then assume another shape or fuse with another 

 protoplasmic body." 



Referring to the theory that the structure of each plant 

 is due to the specific constitution of the protoplasm of the 

 species, Kerner says : 



" What it does not account for is the appropriate manner in which 

 various functions are distributed among the protoplasts of a cell- 

 community ; nor does it explain the purposeful sequence of different 

 operations in the same protoplasm without any change in the 

 external stimuli ; the thorough use made of external advantages ; 

 the resistance to injurious influences ; the avoidance or encompass- 

 ing of insuperable obstacles ; the punctuality with which all the 



