316 FRANCIS DARWIN. 



the aggregation masses were not blackened ; the change was 

 conspicuous and consisted in the transformation of the ropes 

 of aggregation-matter into chains of delicate spheres, re- 

 minding one of rows of dewdrops on a spider's web ;' this 

 change occurred very generally througliout the tentacle. 

 The same kind of formation of minute spheres has been 

 observed in non-aggregated cells exposed to the action of 

 osmic acid. In a leaf allowed to remain during the night in 

 half a watchglass of water to which a few drops of 5 per 

 cent, osmic acid had been added, presented in some cells a 

 similar formation of spheres, while a neighbouring cell 

 was absolutely uninjured and contained cAa;?<7?72<7 aggregation 

 masses. It appears from this that an extremely weak solu- 

 tion of osmic acid is sufficient to alter the appearance of the 

 masses, for the amount absorbed by a tentacle of Avhich any 

 cells remain alive must be very small. 



• Relation of the aggregated masses to the Jlowing Proto- 

 plasm. — In a normal cell before aggregation has commenced 

 the streaming protoplasm does not appear as colourless 

 bands, but as lines of moving granules imbedded in a slightly 

 refracting substance; when, however, the process has well 

 begun, the currents show out clearly as a moving network of 

 colourless granular substance. Daring the process of dis- 

 solution we find cells in which the aggregated masses are 

 nearly dissolved, but which are still divided by narrow divi- 

 sions into a few large masses, nearly filling up the whole 

 cavity of the cell; and in the narrow spaces between the 

 masses currents of protoplasm may sometimes be observed. 

 Again, in the state of intense activity of movement which is 

 produced by subjecting an aggregated tentacle to certain 

 temperatures, one observes small masses of crimson matter 

 forced by the currents to pass between larger masses. 

 The network of flowing protoplasm is continually changing 

 its form, so that it is possible that it may help to mould into 

 shape or divide the aggregated masses. This possibility is 

 obviously favorable to the theory that the changes in the 

 aggregated masses are impressed on them from without. 

 Nevertheless, it is not destructive to my father's hypothesis, 

 for a plastic substance such as protoplasm would naturally be 

 affected by a rapid current like that which streams in the 

 cells of Drosera. 



In strongly aggregated cells the current is invisible or 



' This appearance is possibly similar to the " chains of small globular 

 masses " (* Insectiv. Plants/ p. 207) produced by the action of a strong 

 solution of cobra poison, which, however, is not a poison to Drosera, but 

 merely an intense stimulant. 



