Chap. VII.] OTHER SALTS OF AMMONIA. 



137 



General Summary and Concluding Remarks on the Salts 

 of Ammonia. We have now seen that the nine salts of am- 

 monia which were tried all cause the inflection of the tenta- 

 cles, and often of the blade of the leaf. As far as can be as- 

 certained from the superficial trials with the last six salts, 

 the citrate is the least powerful, and the phosphate certainly 

 by far the most. The tartrate and chloride are remarkable 

 from the short duration of their action. The relative effi- 

 ciency of the carbonate, nitrate, and phosphate, .is shown in 

 the following table by the smallest amount which suffices to 

 cause the inflection of the tentacles. 



Solutions, how applied. 



Carbonate of 

 Ammonia. 



Nitrate of 

 Ammonia. 



Phosphate of 

 Ammonia. 



Placed on the glands of the ' 

 disc, so as to act indirectly 

 ou the outer tentacles . j 



Applied for a few seconds" 

 directly to the gland of an 

 outer tentacle . . . . ^ 



Leaf immersed, with time" 

 allowed for each gland to 

 absorb all that it can . . , 



Amount absorbed by a gland 

 which suffices to cause tiie 

 aggregation of the proto- 

 plasm in the adjoining 

 cells of the tentacles . . 



sio of a 

 grain, or 

 .0675 mg. 



wlinrof a 

 grain, or 

 .00145 mg. 



n^mv of a 

 grain, or 

 .00024 mg. 



TsAvs of a 

 gniin, or 

 .00048 mg. 



tAb of a 

 grain, or 

 .027 mg. 



nisvof a 

 grain, or 

 .0025 mg. 



191100 01 a 



grain, or 



.0000937 mg. 



sAb of a 

 grain, or 

 .0169 mg. 



TT;fcwof a 



grain, or 



.000423 mg. 



lOTniooo 01 a 



gniin. or 



.00000328 rag. 



From the experiments tried in these three different ways, 

 we see that the carbonate, which contains 23.7 per cent, of 

 nitrogen, is less efficient than the nitrate, which contains 35 

 per cent. The phosphate contains less nitrogen than either 

 of these salts, namely, only 21.2 per cent., and yet is far 

 more efficient; its power, no doubt, depending quite as much 

 on the phosphorus as on the nitrogen which it contains. We 

 may infer that this is the case, from the energetic manner in 

 which bits of bone and phosphate of lime affect the leaves. 

 The inflection excited by the other salts of ammonia is prob-' 

 ably due solely to their nitrogen, on the same principle 

 that nitrogenous organic fluids act powerfully, whilst non- 



