66 



DROSEllA ROTUNDIFOLIA, 



\ 



[Chap. IV. 



CHAPTER IV. 



THE EFFECTS OF HEAT ON THE LEA^'E8. 



Nntnre of the experiments Effecta of boiling water Warm water muses 

 nipid inflection Water at a hipher temperature (1(h>.s not cause iiinin'- 

 diute inflection, but Awa not kill the leaves, as shown by their suhw- 

 quent re-expansion and by the aggregation of the protoplasm A still 

 higher temperature kills the leaves and coagulates the albuminous 

 contents of the glands. 



In my observations on Drosera rotundifolia, the leaves 

 seemed to be more quickly inflected over animal substances 

 and to remain inflected for a longer period during very warm 

 than during cold weather. I wished, therefore, to ascertain 

 whether heat alone would induce inflection, and what tem- 

 perature was the most eflScient. Another interesting point 

 presented itself, namely, at what degree life was extin- 

 guished; for Drosera offers unusual facilities in this respect, 

 not in the loss of the power of inflection, but in that of sub- 

 sequent re-expansion, and more especially in the failure of 

 the protoplasm to become aggregated, when the leaves after 

 being heated are immersed in a solution of carbonate of am- 

 monia.' 



' When my experiments on the 

 efTects of heat were made. I wus 

 not aware that the ul>Jeot had 

 been carefully Investigated by 

 several observers. For Instance, 

 Sachs Is convlnce<l (' Trnltf' de 

 Botanlque,' 1874. pp. 772. KA) 

 that the most different kinds of 

 plants all perish If kept for 10 

 m. In water at 40 to id' Cent., 

 or ll.T to 115 Fahr.; and he 

 concludes that the protoplasm 

 within their cells always <'oaKU- 

 lates. If In n dump coinlltlon, nt 

 n temperature or between IV)'' 

 and (50 Cent., or l'J*J to 140' 

 Fnhr. Max S<-hultze and Kllhne 

 (ns (|iioted by Dr. liastlan In 

 Conlemp. Review,' 1874. p. 5281 

 * found that the protoplasm of 

 plnntcells. with which thev ex- 

 perlmenleil. was always killed 

 and altercl by a very brief vx- 



posure to a temperature of 118}* 

 Fiihr. as a maximum." As my 

 results are de<liiced from special 

 phenomena, namely, the subse- 

 quent aggregation of the proto- 

 plasm and the re-expanslon of 

 the tentacles, they seem to me 

 worth giving. We shall find that 

 Drosera resists heat somewhat 

 better than most other plants. 

 That there should be couslder- 

 able differences In this respect Is 

 not surprising, considering that 

 some low vegetable organisms 

 grow In hot springs -cases cf 

 which have been collected by 

 I'rofessor Wyman C American 

 Journal of Science.' vol. xllv. 

 1807). Thus. Dr. Hooker found 

 Confervac In water at m8 Fahr.; 

 Ilntnbcildt. at 1S." Fahr.; and 

 Desclolzeauz, at 'MS Fahr. 



