350 GLANDULAR HAIRS, Chap. XV. 



employed. A solution of this strength paralyses all movement 

 in Drosera, but does not kill the protoplasm ; a still stronger 

 solution prevents the protoplasm from aggregating into the 

 ordinary full-sized globular masses, and these, though they 

 do not disintegrate, become granular and opaque. In nearly 

 the same manner, too hot water and certain solutions (for 

 instance, of the salts of soda and potash) cause at first an 

 imperfect kind of aggregation in the cells of Drosera ; the little 

 masses afterwards breaking up into granular or pulpy brown 

 matter. All the foregoing experiments were made on flower- 

 stems, but a piece of a leaf was immersed for 30 m. in a strong 

 solution of the carbonate (one part to 109 of water), and little 

 globular masses of matter appeared in all the glands, which 

 before contained only limpid fluid. 



I made also several experiments on the action of the vapour 

 of the carbonate on the glands ; but will give only a few cases. 

 The cut end of the footstalk of a young leaf was protected with 

 seahng-wax, and was then placed under a small bell-glass, with 

 a large pinch of the carbonate. After 10 m. the glands showed 

 a considerable degree of aggregation, and the protoplasm lining 

 the cells of the pedicels was a little separated from the walls. 

 Another leaf was left for 50 m. with the same result, excepting 

 that the hairs became throughout their whole length of a 

 brownish colour. In a third leaf, which was exposed for 1 hr. 

 50 m., there was much aggTegated matter in the glands ; and 

 some of the masses showed signs of breaking up into brown 

 granular matter. This leaf was again placed in the vapour, 

 so that it was exposed altogether for 5 hrs. 30 m. ; and now, 

 though I examined a large number of glands, aggregated 

 masses were found in only two or three ; in all the others, 

 the masses, which before had been globular, were converted 

 into brown, opaque, granular matter. We thus see that 

 exposure to the vapour for a considerable time produces the same 

 effects as long immersion in a strong solution. In both cases 

 there could hardly be a doubt that the salt had been absorbed 

 chiefly or exclusively by the glands. 



On another occasion bits of damp fibrin, drops of a weak in- 

 fusion of raw meat and of water, were left for 24 hrs. on some 

 leaves ; the hairs were then examined, but to my surprise differed 

 in no respect from others which had not been touched by these 

 fluids. Most of the cells, however, included hyaline, motionless 

 little spheres, which did not seem to consist of protoplasm, 

 but, I suppose, of some balsam or essential oil. 



Pelargonium zonale (var. edged with white). — The leaves 



