CHAP. III. THE PROCESS OF AGGREGATION. 47 



stream of protoplasm on the walls of the cells coases to be 

 visible ; I observed this fact repeatedly, but will give only one 

 instance. A pale purple leaf was placed in a few drops of a 

 solution of one part to 292 of water, and in 2 hrs. some fine 

 purple spheres were formed in the upper cells of the pedicels, 

 the stream of protoplasm round their walls being still quite 

 distinct ; but after an additional 4 hrs., during which time 

 many more spheres were formed, the stream was no longer 

 distinguishable on the most careful examination ; and this no 

 doubt was due to the contained granules having become united 

 with the spheres, so that nothing was left by which the move- 

 ment of the limpid protoplasm could be perceived. But minute 

 free spheres still travelled up and down the cells, showing that 

 there was still a current. So it was next morning, after 22 hrs., 

 by which time some new minute spheres had been formed ; 

 these oscillated from side to side and changed their positions, 

 proving that the current had not ceased, though no stream of 

 protoplasm was visible. On another occasion, however, a 

 stream was seen flowing round the cell-walls of a vigorous, 

 dark- coloured leaf, after it had been left for 21 hrs. in a rather 

 stronger solution, namely, of one part of the carbonate to 218 of 

 water. This leaf, therefore, was not much or at all injured by 

 an immersion for this length of time in the above solution of 

 two grains to the ounce ; and on being afterwards left for 24 hrs. 

 in water, the aggregated masses in many of the cells were re- 

 dissolved, in the same manner as occurs with leaves in a state of 

 nature when they re-expand after having caught insects. 



In a leaf which had been left for 22 hrs. in a solution of one 

 part of the carbonate to 292 of water, some spheres of proto- 

 plasm (formed by the self-division of a bag-like mass) were 

 gently pressed beneath a covering glass, and then examined 

 under a high power. They were now distinctly divided by 

 well-defined radiating fissures, or were broken up into separate 

 fragments with sharp edges ; and they were solid to the centre. 

 In the larger broken spheres the central part was more opaqiie, 

 darker-coloured, and less brittle than the exterior ; the latter 

 alone being in some cases penetrated by the fissures. In many 

 of the spheres the line of separation between the outer and 

 inner parts was tolerably well defined. The outer parts were of 

 exactly the same very pale purple tint, as that of the last 

 formed smaller sphnvs ; and these latter did not include any 

 darker central core. 



From these several facts we may conclude that when vigorous 

 dark-coloured leaves are subjected to the action of carbonate of 



