Chap. III.] THE PROCESS OP AGGREGATION. 47 



many cells still contained spheres, here and there one could be 

 seen filled with purple fluid, without a vestige of aggregated proto- 

 plasm; the whole having been redissolved. A leaf with aggre- 

 gated masses, caused by its having been waved for 2 m. in water 

 at the temperature of 125 Fahr., was left in cold water, and after 

 11 hrs. the protoplasm showed traces of incipient redissolution. 

 When again examined three days after its immersion in the warm 

 water, there was a conspicuous difference, though the protoplasm 

 was still somewhat aggregated. Another leaf, with the contents of 

 all the cells strongly aggregated from the action of a weak solu- 

 tion of phosphate of ammonia, was left for between three and 

 four days in a mixture (known to be innocuous) of one drachm of 

 alcohol to eight drachms of water, and when re-examined every 

 trace of aggregation had disappeared, the cells being now filled 

 with homogeneous fluid. 



We have seen that leaves immersed for some hours in dense 

 solutions of sugar, gum, and starch have the contents of their cells 

 greatly aggregated, and are rendered more or less flaccid, with the 

 tentacles irregularly contorted. These leaves, after being left for 

 four days in distilled water, became less flaccid, with their ten- 

 tacles partially re-expanded, and the aggregated masses of proto- 

 plasm were partially redissolved. A leaf with its tentacles closely 

 clasped over a fly, and with the contents of the cells strongly 

 aggregated, was placed in a little sheny wine; after 2 hrs. several 

 of the tentacles had re-expanded, and the others could by a mere 

 touch be pushed back into their properly expanded positions, and 

 now all traces of aggregation had disappeared, the cells being filled 

 with perfectly homogeneous pink fluid. The redissolution in these 

 cases may, I presume, be attributed to endosmose. 



On the Proximate Causes of the Process of Aggregation. 



As most of the stimulants which cause the inflection ai 

 the tentacles likewise induce aggregation in the contents of 

 their cells, this latter process might be thought to be the 

 direct result of inflection ; but this is not the case. If leaves 

 are placed in rather strong solutions of carbonate of am- 

 monia, for instance of three or four, and even sometimes of 

 only two grains to the ounce of water (i. e. one part to 109, or 

 146, or 218, of water), the tentacles are paralyzed, and do 

 not become inflected, yet they soon exhibit strongly marked 

 aggregation. Moreover, the short central tentacles of a leaf 

 which has been immersed in a weak solution of any salt of 

 ammonia, or in any nitrogenous organic fluid, do not become 

 in the least inflected; nevertheless, they exhibit all the phe- 

 nomena of aggregation. On the other hand, several acids 

 cause strongly pronoimccd inflection, but no aggregation. 



