6G DROSERA EOTUNDIFOIJA. [Chap. V. 



Olive Oil. Drops were placed on the discs of eleven leaves, and 

 no effect was produced in from 24 hrs. to 48 hrs. Four of these 

 leaves were then tested by bits of meat on their discs, and three of 

 them were found after 24 hrs. with all their tentacles and blades 

 closely inflected, whilst the fourth had only a few tentacles inflected. 

 It will, however, be shown in a future place, that cut-off leaves im- 

 mersed in olive oil are powerfully affected. 



Infusion and Decoction of Tea. Drops of a strong infusion and 

 decoction, as well as of a rather weak decoction, of tea were placed 

 on ten leaves, none of which became infected. I afterwards tested 

 three of them by adding bits of meat to the drops which still re- 

 mained on their discs, and when I examined them after 24 hrs. they 

 were closely inflected. The chemical principle of tea, namely theine, 

 was subsequently tried and produceii no effect. The albuminous 

 matter which the leaves must riginally have contained, no doubt, 

 had been rendered insoluble by their having been completely dried. 



We thus see that, excluding the experiments with water, 

 sixty-one leaves were tried with drops of the above-named 

 non-nitrogenous fluids; and the tentacles were not in a 

 single case inflected. 



With respect to nitrogenous fluids, the first which came to hand 

 were tried. The experiments were made at the same time and in 

 exactly the same manner as the foregoing. As it was immediately 

 evident that these fluids produced a great effect, I neglected in most 

 cases to record how soon the tentacles became inflected. But this 

 always occurred in less than 24 hrs.; whilst the drops of non- 

 nitrogenous fluids which produced no effect were observed in every 

 case during a considerably longer period. 



Milk. Drops were placed on sixteen leaves, and the tentacles of 

 all, as well as the blades of several, soon became greatly inflected. 

 The periods were recorded in only three cases, namely, with leaves 

 on which unusually small drops had been placed. Their tentacles 

 were somewhat inflected in 45 m. ; and after 7 hrs. 45 m. the blades 

 of two were so much curved inwards that they formed little cups 

 enclosing the drops. These leaves re-expanded on the third day. On 

 another occasion the blade of a leaf was much inflected in 5 hrs. 

 after a drop of milk had been placed on it. 



Human Urine. Drops were placed on twelve leaves, and the ten- 

 tacles of all, with a single exception, became greatly inflected. Ow- 

 ing, I presume, to differences in the chemical nature of the urine 

 on different occasions, the time required for the movements of the 

 tentacles varie<l much, but was always effected in under 24 hrs. In 

 two instances I recorded that all the exterior tentacles were com- 

 pletely inflected in 17 hrs., but not the blade of the leaf. In another 

 case the edges of a leaf, after 25 hrs. 30 m.. became so strongly in- 

 flected that it was converte<l into a cup. The power of urine does 

 not lie in the urea, which, as we shall hereafter see, is inoperative. 



Albumen (fresh from a hen's egg), placed on seven leaves, caused 



