44 DROSERA ROTUNDIFOLIA. Chap. HI. 



darken in 10 s. (seconds); and in 13 s. were conspicnonsly 

 darker. In 1 m. extremely small splierical masses of protoplasm 

 could be seen arising in the cells of the pedicels close beneath 

 the glands, as well as in the cushions on which the long- 

 headed marginal glands rest. In several cases the process 

 travelled down the pedicels for a length twice or thrice as great 

 as that of the glands, in about 10 m. It was interesting to 

 observe the process momentarily arrested at each transverse 

 partition between two cells, and then to see the transparent 

 contents of the cell next below almost flashing into a cloudy 

 mass. In the lower part of the pedicels, the action proceeded 

 slower, so that it took about 20 m. before the cells halfway 

 down the long marginal and submarginal tentacles became 

 aggregated. 

 ^ We may infer that the carbonate of ammonia is absorbed by 

 the glands, not only from its action being so rapid, but from its 

 eifcct being somewhat different from that of other salts. As the 

 glands, when excited, secrete an acid belonging to the acetic 

 series, the carbonate is probably at once converted into a 

 salt of this series ; and we shall presently see that the acetate 

 of ammonia causes aggregation almost or quite as energetically 

 as does the carbonate. If a few drops of a solution of one part of 

 the carbonate to 437 of water (or 1 gr. to 1 oz.) be added to the 

 purple fluid which exudes from crushed tentacles, or to paper 

 stamed by being rubbed with them, the fluid and the paper are 

 changed into a pale dirty green. Nevertheless, some purple 

 colour could still be detected after 1 hr. 30 m. within the glands 

 of a leaf left in a solution of twice the above strength (viz. 

 2 gi"s. to 1 oz.) ; and after 24 hrs. the cells of the pedicels close 

 beneath the glands still contained spheres of protoplasm of a 

 fine purple tint. These facts show that the ammonia had not 

 entered as a carbonate, for otherwise the colour would have 

 been discharged. I have, however, sometimes observed, espe- 

 cially with the long-headed tentacles on the margins of very pale 

 leaves immersed in a solution, that the glands as well as the 

 upper cells of the pedicels were discoloured; and in these cases 

 I presume that the unchanged carbonate had been absorbed. 

 The appearance above described, of the aggregating process 

 lx}ing arrested for a short time at each transverse partition, 

 impresses the mind with the idea of matter passing downwards 

 from cell to cell. But as the cells one beneath the other 

 undergo aggregation when inorganic and insoluble particles are 

 placed on the glands, the process must be, at least in these 

 cases, one of molecular change, transmitted from the glands. 



