AGGREGATION IN THE TENTACLES OF DROSERA. 315 



withstand the action of strong reagents. In order that the 

 tints produced by the reactions may be perceptible, it is es- 

 sential that very pale leaves should be selected ; the dwarfed 

 plants growing hidden in moss answer this purpose well. 



The masses are not soluble in absolute alcohol or in a mix- 

 ture of turpentine and creasote ; either of these would dis- 

 solve oils ; the aggregated masses are therefore not purely 

 oleaginous. 



They are not coloured blue by iodide or by Schultze's solu- 

 tion, and therefore are probably not amylaceous. A pale 

 aggregated tentacle placed in a solution of caustic potash 

 assumes a yellow tint ; the masses not being dissolved ; 

 on removing the superfluous alkali and adding strong nitric 

 acid the masses assume the orange-yellow colour of xantho- 

 protein. If a tentacle is placed in syrup and afterwards in 

 strong sulphuric acid, the masses become reddish brown. 



The aggregated masses (in a tentacle killed by osmic acid) 

 are stained yellow by iodine. The three last-mentioned reactions 

 are given by Sachs^ as tests for protoplasm. But we must not 

 therefore conclude that the aggregated masses consist of pro- 

 toplasm ; for Sachs adds that the above-mentioned reactions 

 are characteristic of " true albuminoids as caseine, fibrine, 

 albumen. We are at least justified in assuming that the 

 aggregated masses consist of albuminoid substances. 



A tentacle was placed in strong solution of htematoxylin 

 (which acted, I presume, as a poison) ; the staining fluid was 

 absorbed at one of the minute papillae and the aggregated 

 masses in the neighbouring cells became brightly tinted 

 with it. The power of absorbing colouring matter is men- 

 tioned by Sachs as a characteristic of dead protoplasm and 

 other albuminoid bodies. 



The action of osmic acid on the tentacles was not satisfac- 

 torily made out. The aggregated masses of tentacles placed 

 in \ per cent, solution of this acid, are intensely black- 

 ened and are fairly well preserved from the degeneration into 

 granular debris which is the usual result of the death of an 

 aggregated cell. But in some cases osmic acid seems to alter 

 the appearances of the aggregated masses before the death 

 of the cell is caused. Thus in one instance I mounted in 

 water a tentacle in which there were fine ropelike masses of 

 aggregated matter. I then irrigated the preparation with 

 about three drops of \ per cent, osmic acid ; it was chiefly 

 absorbed at the cut-off" end of the tentacle, where it black- 

 ened the aggregated masses ; but in cells further removed 

 from the cut surface a distinct eflfect was produced although 

 » 'Handbook,'?. 40, 



