46 DROSERA ROTUNDIFOLIA. [Chap. III. 



wfts submerged in distilled water for 47 hre., and the frlnnds were 

 MackeniHl, though the tentat'lcs were very little inflected. In one 

 of these leaves there was only a slight degree of aggregation in 

 the tentacles; in the second rather more, the purple contents of the 

 cells being a little separated from the walls; in the third and 

 fourth, which were pale leaves, the aggregation in the upper parta 

 of the iHHlicels was well niarkwl. In these leaves the little masses 

 of protoplasm, many of which were oval, slowly changed their 

 fomis and positions; so that a submergence for 47 hrs. had not 

 killed the protoplasm. In a previous trial with a submerged plant 

 the tentacles were not in the least inflected. 



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

 tacles containing only homogeneous fluid, was wave<l about for 1 m. 

 in water at 130 Fahr. {54*'.4 Cent.), and was then examineil 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 

 12,5 (51.0 Cent.) and quickly examined as before; the tentacles 

 were well inflectetl ; 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 di(l not subsecjuently 

 increase. Lastly, a leaf was waved for 1 m. in water at 120 (4S.8 

 Cent.) and then left for 1 hr. 20 m. in cold water; the tentacles 

 were but little inflecte<l, and there was only here and there a trace 

 of aggregation. In all these and other trials with warm water the 

 protoplasm showetl much less tendency to aggregate into spherical 

 masses than when excited by carbonate of ammonia. 



Redissohition <if the Angrrynted ManKcn of Prntnphmm. As soon 

 as tentacles which have clasped an insect or any inorganic object, or 

 have been in any way excited, have fully re-expan<led, the aggre- 

 gated mas-ses of protoplasiH are redissolved and disappear; the cells 

 being now refille<l with homogeneous purple fluid as they were 

 before the tentacles were inflected. The process of redissolution in 

 all cases commences at the bases of the tentacles, and proce<Mls up 

 them towards the glands. In old leaves, however, es|>ecially 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 condition. In order to observe the process of 

 redisaolution, the following observations were made: a leaf was 

 left for 24 hrs. in a little solution of one part of carbonate of am- 

 monia to 218 of water, and the protoplasm was as usual aggregated 

 into numl>erles8 purple spheres, which were incessantly changing 

 their forms. The leaf was then washe<l an<l place<l in distilled 

 water, and after 3 hrs. 15 m. some few of the spheres l>egan to 

 show by their less clearly defined edges signs of redissolution. 

 After O' hrs. many of them had become elongate<l, and the sur- 

 rounding fluid in the cells was slightly more coloure<l, showing 

 plainly that redissolution bad commenced. After 24 hrs., though 



