The Influence of the Nucleus in the Cell 189 



can, it is true, produce starch and nourish themselves, 

 but they are not able to grow. 



In order to get more information on the role of the 

 nucleus a method would evidently be needed, which would 

 allow us to kill the nucleus without injuring the cell body. 

 Perhaps this end could be attained by making use of the 

 method suggested by Pringsheim, of partially killing the 

 cells in the focal point of a lens. 42 By selecting a lens 

 that makes it possible to strike a single point of the cell, 

 it could be focused on the nucleus with a dim light, and 

 then a brief exposure to the direct rays of the sun might 

 produce the desired result in some of the cells. I there- 

 fore warmly recommend this method for further elabo- 

 ration in this direction. 



In reviewing the results of the investigations that 

 have been discussed, we see that the nuclei have an in- 

 fluence on the activity of the other members of the proto- 

 plast. They exercise this influence only as long as the 

 respective members remain in the most intimate proto- 

 plasmic connection with them, preferably at the shortest 

 possible distance, or otherwise by direct plasma-bands. 



42 Pringsheim, N. Jahrb. Wiss. Bot. 12: 331. 1881. 



