Chap. III.] THE PROCESS OP AGGREGATION. 55 



a grain, or 2.024 mg. When examined, the cells of all the roots 

 throughout their whole length contained aggregated masses of 

 reddish and brown matter. Before making these experiments, sev- 

 eral roots were closely examined, and not a trace of the cloudy 

 appearance or of the granular masses could be seen in any of them. 

 Roots were also immersed for 35 m. in a solution of one part of car- 

 bonate of potash to 218 of water; but this salt produced no effect. 



I may here add that thin slices of the stem of the Euphorbia 

 were placed in the same solution, and the cells which were green 

 instantly became cloudy, whilst others which were before colour- 

 less were clouded with brown, owing to the formation of numerous 

 granules of this tint. I have also seen with various kinds of 

 leaves, left for some time in a solution of carbonate of ammonia, 

 that the grains of chlorophyll ran together and partially coalesced; 

 and this seems to be a form of aggregation. 



Plants of duck- weed (Lemna) were left for between 30 m. and 

 45 m. in a solution of one part of this same salt to 146 of water, 

 and three of their roots were then examined. In two of them, all 

 the cells which had previously contained only limpid fluid now in- 

 cluded little green spheres. After from H hr. to 2 hrs. similar 

 spheres appeared in the cells on the borders of the leaves; but 

 whether the ammonia had travelled up the roots or had been 

 directly absorbed by the leaves, I can not say. As one species, 

 Lemna arrhiza, produces no roots, the latter alternative is per- 

 haps the most probahle. After 2J hrs. some of the little green 

 spheres in the roots were broken up into small granules which ex- 

 hibited Brownian movements. Some duck-weed was also left for 

 1 hr. 30 m. in a solution of one part of carbonate of potash to 218 

 of water, and no decided change could be perceived in the cells 

 of the roots: but when these same roots wero,placed for 25 m. in 

 a solution of carbonate of ammonia of the same strength, little 

 green spheres were formed. 



A green marine alga was left for some time in this same solu- 

 tion, but was very doubtfully affected. On the other hand, a red 

 marine alga, with finely pinnated fronds, was strongly affected. 

 The contents of the cells aggregated themselves into broken rings, 

 still of a red colour, which very slowly and slightly changed their 

 shapes, and the central spaces within these rings became cloudy 

 with red granular matter. The facts here given (whether they are 

 new, I know not) indicate that interesting results would perhaps 

 be gained by observing the action of various saline solutions and 

 other fluids on the roots of plants." 



" [Bee C. Darwin on " The Ac- tlon of Carbonate of Ammonia 



tlon of Carbonate of Ammonia on Chioroph.vli-l)o<lles: " * Linn. 



on the Roots of certain Plants: " Soc. Jonrmil ' (Rot.), vol. xlx. 



' Linn. Soc. Jonrnnl ' (Bot.), vol. 1882, p. 2G2. F. D.l 

 xlx. 1882, p. 230; also The Ac- 



