-. III. THE PROCESS OF AGGREGATION. 53 



Heat induces aggregation. A leaf, with the cells of the 

 tentacles containing only homogeneous fluid, was waved about 

 for 1 m. in water at 130 Fahr. (54'4 Cent.), and was then 

 examined under the microscope as quickly as possible, that 

 is in 2 m. or 3 m. ; and by this time the contents of the 

 cells had undergone some degree of aggregation. A second leaf 

 was waved for 2 m. in water at 125 (51 0> 6 Cent.) and quickly 

 examined as before ; the tentacles were well inflected ; the 

 purple fluid in all the cells had shrunk a little from the walls, 

 and contained many oval and elongated masses of protoplasm, 

 with a few minute spheres. A third leaf was left in water at 

 125, until it cooled, and when examined after 1 hr. 45 m., the 

 inflected tentacles showed some aggregation, which became 

 after 3 hrs. more strongly marked, but did not subsequently 

 increase. Lastly, a leaf was waved for 1 m. in water at 12CP 

 (48'8 Cent.) and then left for 1 hr. 26 m. in cold water ; the 

 tentacles were but little inflected, and there was only here and 

 there a trace of aggregation. In all these and other trials 

 with warm water the protoplasm showed much less tendency 

 to aggregate into spherical masses than when excited by car- 

 bonate of ammonia. 



Redissolution of the Aggregated Masses of Protoplasm. As soon 

 as tentacles which have clasped an insect or any inorganic 

 object, or have been in any way excited, have fully re-expanded, 

 the aggregated masses of protoplasm are redissolved and dis- 

 appear ; the cells being now refilled with homogeneous purple 

 fluid as they were before the tentacles were inflected. The 

 process of reclissolution in all cases commences at the bases of the 

 tentacles, and proceeds up them towards the glands. In old 

 leaves, however, especially in those which have been several 

 times in action, the protoplasm in the uppermost cells of the 

 pedicels remains in a permanently more or less aggregated con- 

 dition. In order to observe the process of redissolution, the 

 following observations were made : a leaf was left for 24 hrs. in 

 a little solution of one part of carbonate of ammonia to 218 of 

 water, and the protoplasm was as usual aggregated into number- 

 less purple spheres, which were incessantly changing their 

 forms. The leaf was then washed and placed in distilled water, 

 and after 3 hrs. 15 m. some few of the spheres began to show by 

 their less clearly denned edges signs of redissolution. After 

 9 hrs. many of them had become elongated, and the surround- 

 ing fluid in the cells was slightly more coloured, showing 

 plainly that redissolution had commenced. After 24 hrs., 

 though many cells still contained spheres, here and there one 



