CHAP. VII. CAKBONATE OF AMMONIA. 145 



tentacles become inflected within the same time, we have 

 evidence, as before remarked, of simultaneous absorption. I 

 did not count the number of glands on these four leaves ; but 

 as they were fine ones, and as we know that the average number 

 of glands on thirty-one leaves was 192, we may safely assume 

 that each bore on an average at least 170; and if so, each 

 blackened gland could have absorbed only 54 ^ od of a grain 

 ('00119 mg.) of the carbonate. 



A large number of trials had been previously made with 

 solutions of one part of the nitrate and phosphate of ammonia to 

 43750 of water (i.e. one grain to 100 ounces), and these were 

 found highly efficient. Fourteen leaves were therefore placed, 

 each in thirty minims of a solution of one part of the carbonate 

 to the above quantity of water ; so that each leaf received y^ 

 of a grain ('0405 mg.). The glands were not much darkened. 

 Ten of the leaves were not affected, or only very slightly so. 

 Four, however, were strongly affected ; the first having all the 

 tentacles, except forty, inflected in 47 m. ; in 6 hrs. 30 m. all 

 except eight ; and after 4 hrs. the blade itself. The second leaf 

 after 9 m. had all its tentacles except nine inflected ; after 6 hrs. 

 30 m. these nine were sub-inflected ; the blade having become 

 much inflected in 4 hrs. The third leaf after 1 hr. 6 m. had all 

 but forty tentacles inflected. The fourth, after 2 hrs. 5 m., had 

 about half its tentacles and after 4 hrs. all but forty-five in- 

 flected. Leaves which were immersed in water at the same time 

 were not at all affected, with the exception of one ; and this not 

 until 8 hrs. had elapsed. Hence there can be no doubt that a 

 highly sensitive leaf, if immersed in a solution, so that all the 

 glands are enabled to absorb, is acted on by y^ of a grain of 

 the carbonate. Assuming that the leaf, which was a large one, 

 and which had all its tentacles excepting eight inflected, bore 

 170 glands, each gland could have absorbed only 2^-hoo f a 

 grain ( 00024 mg.) ; yet this sufficed to act on each of the 162 

 tentacles which were inflected. But as only four out of the above 

 fourteen leaves were plainly affected, this is nearly the mini- 

 mum dose which is efficient. 



Aggregation of the Protoplasm from the Action of Carbonate of 

 Ammonia. I have fully described in the third chapter the 

 remarkable effects of moderately strong doses of this salt in 

 causing the aggregation of the protoplasm within the cells of 

 the glands and tentacles ; and here my object is merely to show 

 what small doses suffice. A leaf was immersed in twenty 

 minims (1 183 ml.) of a solution of one part to 1750 of water 



