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Show 144 DROSERA ROTUNDIFOLIA. CHAP. VII. __1_ _ of a grain (' 00445 mg.). Nevertheless, in two trials all t1h4e4 0g0l ands were plainly blackened ; I. n one case a 11 t h ree tentacles were well inflected after an interval of 2 hrs. 40 m.; and in another case two of the three tentacles were inflected. I then tried drops of a weaker solution of one part to 292 of water on twenty-four glands, always touching the viscid secretion round three glands with the same little drop. Each gland thus received only the___],_ __ of a grain ('00337 mg.), yet some of them were 19200 • • t f' a little darkened; but m no one Ins ance were any o the ten-tacles inflected, though they were watched for 1~ hrs. When a still weaker solution (viz. one part to 437 of water) was tried on six glands, no effect whatever was perceptible. We thus learn that the _1_ of a grain ('00445 mg.) of carbonate of ammonia if absorb~~t-b; a gla.nd, suffices to induce inflection in the basai part of the same tentacle; but as already stated, I was able to hold with a steady hand the minute drops in contact with the secretion only for a few seconds ; and if more time had been allowed for diffusion and absorption, a much weaker solution would certainly have acted. Some experiments were made by immersing cut-off leaves in solutions of different strengths. Thus four leaves were left for about 3 hrs. each in a drachm (3 · 549 ml.) of a solution of one part of the carbonate to 5250 of water; two of these had almost every tentacle inflected, the third had about half the tentacles and the fourth about one-third inflected; and all the glands were blackened. .Another leaf was placed in the same quantity of a solution of one part to 7000 of water, and in 1 hr. 16 m. every single tentacle was well inflected, and all the glands blackened. Six leaves were immersed, each in thirty minims (1· 77 4 ml.) of a solution of one part to 4375 of water, and the glands were all blackened in 31m. All six leaves exhibited some slight inflection, and one was strongly inflected. Four leaves were then immersed in thirty minims of a solution of one part to 8750 of water, so that each leaf received the alo of a grain ( · 2025 mg.). Only one became strongly inflected; but all the glands on all the leaves were of so dark a red after one hour as almost to deserve to be called black, whereas this did not occur with the leaves which were at the same time immersed in water; nor did water produce this effect on any other occasion in nearly so short a time as an hour. These cases of the simultaneous darkening or blackening of the glands from the action of weak solutions are important, as they show that all the glands absorbed tho carbonate within the same time, which fact indeed there was not the least reason to doubt. So again, whenever all the CHAP. VII. CARBONATE OF AMMONIA. 145 tentacles become inflected within the same time we hav e:idence, as before remarked, of simultaneous abs~rption. i d1d 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 __ _1 __ of a ara1·n 5-1!400 b ('00119 mg.) of the carbonate. A large number of trials had buen 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 those were found highly efficient. Fourteen leaves were therefore placed each in thirty minims of a solution of one part of the carbonat~ to the above quantity of water; so that each leaf received __ ] __ of a grain ( · 0405 mg.). The glands were not much darko~6od~ Ten of the leaves were not affected, or only very slightly so. Fo1,1r, however, were strongly affected; the first having all the tentacle~, except forty, inflected in 47 m.; in 6 hrs. 30 m. all except mght; 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 ha~inO' becom~ much inflected in 4 hrs. The third leaf after 1 hr. 6 ~.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 inflected. Leaves which were immersed in water at the same time wer~ not at all affected, with the exception of one; and this not u~til 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 16 1 00 of a grain of the car?onate. Ass~1ming that the leaf, which was a large one, and whiCh had all Its tentacles excepting eight inflected bore 170_ glands, each gland could ha~e absorbed only 268 1'0 00 , of 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 minimum dose which is efficient. Aggre?ation of tlte Protoplasm from the Action rif Carbonate of Ammonta.-l have fully described in the third chapter the rem~rkable effects of moderately strong doses of this salt in causmg the aggregation of the protoplaRm within the cells of the glands and tentacles; and here my object is merely to show w~a~ small doses suffice. A leaf was immersed in twenty munms (1·183 mi.) of a solution of one part to 1750 of water; L |