GROWTH AND SENESCENCE OF THE CELL 



279 



only in degenerating tissues decreasing in energy and approach- 

 ing the end of the senescent period. Recent investigations have 

 shown however, that the method of division is highly susceptible 

 to external influences and that mitosis may be inhibited for gen- 

 erations of cells, and that the descendants by amitotic division 

 exhibit no differences from those resulting from division with mi- 

 tosis of the nucleus. 2 



356. Growth and Senescence of the Cell. After a daughter 

 cell has been formed by the division of a generative element, it 



A 



ft 





FIG. 132. Nuclei of older internodes of Tradescantia Virginica, in indirect, or 

 amitotic division. A, view of living nuclei. B, nuclei after treatment with acetic 

 methyl-green. After Strasburger. 



may divide one or more times, but it, or its derivatives, will fol- 

 low a course similar to that described below. The protoplast at 

 first consists of a nucleus which occupies the larger share of the 

 volume of the cell, and a comparatively small amount of cyto- 

 plasm, which is free from vacuoles. The latter contains a large 



2 Nathansohn, A. Physiologische Untersuchungen ueber amitotische Kerntheilung. 

 Jahrb. Wiss. Bot. 35 : 48. 1900. 



