270 DROSEEA ROTUNDIFOLIA. CHAP. XI 



of the seedlings. It also absorbs matter from pollen, 

 and from fragments of leaves. 



The seventh chapter was devoted to the action of 

 the salts of ammonia. These all cause the tentacles, 

 and often the blade of the leaf, to be inflected, and 

 the protoplasm to be aggregated. They act with very 

 different power ; the citrate being the least powerful, 

 and the phosphate, owing, no doubt, to the presence 

 of phosphorus and nitrogen, by far the most powerful. 

 T3ut the relative efficiency of only three salts of 

 ammonia was carefully determined, namely the car- 

 bonate, nitrate, and phosphate. The experiments were 

 made by placing half-minims ('0296 ml.) of solutions 

 of different strengths on the discs of the leaves, by 

 applying a minute drop (about the -^^ of a minim, or 

 00296 ml.) for a few seconds to three or four glands, 

 and by the immersion of whole leaves in a measured 

 quantity. In relation to these experiments it was 

 necessary first to ascertain the effects of distilled water, 

 and it was found, as described in detail, that the more 

 sensitive leaves are affected by it, but only in a slight 

 degree. 



A solution of the carbonate is absorbed by the roots 

 and induces aggregation in their cells, but does not 

 affect the leaves. The vapour is absorbed by the 

 glands, and causes inflection as well as aggregation. 

 A drop of a solution containing -^-^ of a grain 

 (0675 mg.) is the least quantity which, when placed 

 on the glands of the disc, excites the exterior ten- 

 tacles to bend inwards. But a minute drop, contain- 

 ing , 4 i o o f a grain ('00445 mg.), if applied for a few 

 seconds to the secretion surrounding a gland, causes 

 the inflection of the same tentacle. When a highly 

 sensitive leaf is immersed in a solution, and there is 

 ample time for absorption, the a 6 8 ' 8 of a grain 



