184 DROSERA ROTUNDIFOLIA. [Chap. IX 



exhibited incessant changes of form, but after 24 hrs. were 

 motionless; the leaf being flaccid and apparently dead. On 

 the other hand, with leaves subjected for 48 hrs. to a strong 

 solution of the poison of the cobra, the protoplasmic masses 

 were unusually active, whilst with the higher animals the vi- 

 bratile cilia and white corpuscles of the blood seem to be 

 quickly paral^'sed by this substance. 



With the salts of alkalies and earths, the nature of the 

 base, and not that of the acid, determines their physiological 

 action on Drosera, as is likewise the case with animals; but 

 this rule hardly applies to the salts of quinine and strych- 

 nine, for the acetate of quinine causes much more inflection 

 than the sulphate, and both are poisonous, whereas the 

 nitrate of quinine is not poisonous, and induces inflection at 

 a much slower rate than the acetate. The action of the 

 citrate of strychnine is also somewhat different from that of 

 the sulphate. 



Leaves which have been immersed for 24 hrs. in water, 

 and for only 20 m. in diluted alcohol, or in a weak solution 

 of sugar, are afterwards acted on very slowly, or not at all, 

 by the phosphate of ammonia, though they are quickly acted 

 on by the carbonate. Immersion for 20 m. in a solution of 

 gum arable has no such inhibitory power. The solutions of 

 certain salts and acids affect the leaves, with respect to the 

 subsequent action of the phosphate, exactly like water, whilst 

 others allow the phosphate afterwards to act quickly and 

 energetically. In this latter case, the interstices of the cell- 

 walls may have been blocked up by the molecules of the 

 salts first given in solution, so that water could not after- 

 wards enter, though the molecules of the phosphate could do 

 80, and those of the carbonate still more easily. 



The action of camphor dissolved in water is remarkable, 

 for it not only soon induces inflection, but apparently renders 

 the glands extremely sensitive to mechanical irritation; for 

 if they are brushed with a soft brush, after being immersed 

 in the solution for a short time, the tentacles begin to bend 

 in about 2 m. It may, however, be that the brushing, though 

 not a sufficient stimulus by itself, tends to excite movement 

 merely by reinforcing the direct action of the camphor. The 

 vapour of camphor, on the other hand, serves as a narcotic. 



Some essential oils, both in solution and in vapour, cause 



