136 DEOSEKA ROTUNDIFOLIA. Chap. VIL 



CHAPTER VII. 



The Effects of Salts of Ammonia. 



Manner of performing the experiments — Action of distilled water in 

 comparison with the solutions — Carbonate of ammonia, absorbed 

 by the roots — The vapour absorbed by the glands — Drops on the 

 disc — Minute drops applied to separate glands — Leaves im- 

 mersed in weak solutions — Minuteness of the doses which induce 

 aggregation of the protoplasm — Nitrate of ammonia, analogous 

 experiments with — Phosphate of ammonia, analogous experiments 

 with — Other salts of ammonia — Summary and concluding re- 

 marks on the action of the salts of ammonia. 



The chief object in this chapter is to show how power- 

 fully the salts of ammonia act on the leaves of Drosera, 

 and more especially to show what an extraordinarily 

 small quantity suffices to excite inflection. I shall, 

 therefore, be compelled to enter into full details. 

 Doubly distilled water was always used ; and for the 

 more delicate experiments, water which had been 

 prepared with the utmost possible care was given 

 me by Professor Frankland. The graduated measures 

 were tested, and found as accurate as such measures 

 can be. The salts were carefully weighed, and in all 

 the more delicate experiments, by Borda's double 

 method. But extreme accuracy would have been 

 superfluous, as the leaves differ greatly in irritability, 

 according to age, condition, and constitution. Even 

 the tentacles on the same leaf differ in irritability 

 to a marked degree. My experiments were tried in 

 the following several ways. 



Firsihj.— Droits which were ascertained by repeated trials to 

 be on an average about half a minim, or the q-}^ of a fluid ounce 

 (-0296 ml.), were placed by the same pointed instrument on the 



