5S0 - Douglas H. Campbell. 



Ihe protoplasm still quite active. In Ihe dahlia Solution all the hairs were 

 still uncolored but after leaving them for about three hours longer, several 

 had the nuclei unmistakeably stained, but not so well as with mauvein, and 

 Ihe cell-wall was also more or less colored. 



Cucurbita pepo L. 



The root-hairs of Cucurbita show active Streaming and take up the co- 

 loring fluids readily, but the protoplasm is colored as deeply as the nu- 

 cleus, and the latter not being very definite in outline is not well difle- 

 rentiated. 



In Order to obtain the hairs, the seeds were germinated in meist saw- 

 dust and then removed and placed under a bell jar in which the air was 

 kept saturated with moisture. In this atmosphere new root-hairs are formed 

 in great numbers. 



Experiments with pollen-tubes. 



A number of experiments were made with pollen-tubes, but owing to 

 the density of the protoplasm the coloring of the nucleus could not be posi- 

 tively demonstrated. 



The foUowing were found to germinate freely in a \^% cane-sugar 

 Solution, to which a very small amount of dahlia or mauvein was added : — 

 Lilium candidum, Tradescantia virginica, Scilla spec. In all there is well- 

 marked Streaming of the protoplasm in the pollen-tube, and the color is 

 readily absorbed, but the protoplasm stains so deeply and the nuclei are so 

 indistinct, that it is impossible to say whether the latter are colored 

 or not. 



Algae. 



Various species of Spirogyra and Zygnema were tried, but either the 

 cells were killed or the cell-contents were so dense as to prevent a satis- 

 factory study of the nucleus. 



Parts of the nucleus stained. 



When nucleoli are present, these appear to be always stained and are 

 conspicuous. The microsomes are often well-differentiated, but the inter- 

 mediate substance appears to be little or not at all colored. Further in- 

 vestigations, however, are necessary to determine exactiy what parts are 

 stained and the more intimate structure of the nucleus. As far as could be 

 determined, the living nucleus conducts itself toward these coloring agents 

 in much the same way as nuclei fixed by alcohol or any of the ordinary 

 hardening agents, do toward the common staining agents. 



Conclusions reached. 

 The results of the foregoing experiments may be briefly summed up 

 as follows. 



