34 DROSERA ROTUNDIFOLIA. [Chap. TTT. 



crushed; some degree of aggrregation having been thus al- 

 most instantly caused. 



If a tentacle is examined some hours after the gland has 

 been excited by repeated touches, or by an inorganic or or- 

 ganic particle placed on it, or by the absorption of certain 

 fluids, it presents a wholly changed appearance. The cells, 

 instead of being filled with homogeneous purple fluid, now 

 contain variously shaped masses of purple matter, suspended 

 in a colourless or almost colourless fluid. The change is so 

 conspicuous that it is visible through a weak lens, and even 

 sometimes with the naked eye; the tentacles now have a mot- 

 tled appearance, so that one thus affected can be picked out 

 with ease from all the others. The same result follows if 

 the glands on the disc are irritated in any manner, so that 

 the exterior tentacles become inflected; for their contents 

 will then be found in an aggregated condition, although their 

 glands have not as yet touched any object. But aggregation 

 may occur independently of inflection, as we shall presently 

 see. By whatever cause the process may have been excited, 

 it commences within the glands, and then travels down the 

 tentacles. It can be observed much more distinctly in the 

 upper cells of the pedicels than within the glands, as these 

 are somewhat opaque. Shortly after the tentacles have re- 

 expanded, the little masses of protoplasm are all redissolved, 

 and the purple fluid within the cells becomes as homogeneous 

 and transparent as it was at first. The process of redissolu- 

 tion travels upwards from the bases of the tentacles to the 

 glands, and therefore in a reversed direction to that of aggre- 

 gation. Tentacles in an aggregated condition were shown 

 to Prof. Huxley, Dr. Hooker, and Dr. Burdon Sanderson, 

 who observed the changes under the microscope, and were 

 much struck with the whole phenomenon. 



The little masses of aggregated matter are of the most 

 diversified shapes, often spherical or oval, sometimes much 

 elongated, or quite irr^^lar with thread- or necklace-like or 

 club-formed projections. They consist of thick, apparently 

 viscid matter, which in the exterior tentacles is of a purplish, 

 and in the short discal tentacles of a greenish, colour. These 

 little masses incessantly change their forms and positions, be- 

 ing nevet at rest. A single mass will often separate into two, 

 which afterwards reunite. Their movements are rather 



