118 DROSERA ROTUNDIFOLIA. [Chap. VIL 



well inflectwl, and all the glands blackened. Six leaves were im- 

 nioi-sed, each in thirty minims (1.774 c.e.) of a solution of one 

 part to 4375 of water, and the glands were all blackened in 31 m. 

 All six leaves exhibited some slight inflection, and one was strongly 

 inflected. Four leaves were then immersed in thirty minims ot a 

 solution of one part to 8750 of water, so that each leaf received the 

 x^ of a grain (.2025 nig.). 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 so* 

 lutions are important, as they show that all the glands absorbed the 

 carbonate within the same time, which fact indeed there was not 

 the least reason to doubt. So again, whenever all the tentacles be- 

 come 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 ko, each blackened gland could have absorbed 

 o^^Jy rriini ^ * grain (.00119 mg.) of the carbonate. 



A large number of trials had been previously made with solu- 

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

 43750 of water (t. c. one grain to 100 ounces), and these were found 

 highly efTicient. 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, how- 

 ever, were strongly affected; the first having all the tentacles, ex- 

 cept 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. 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 inflected. leaves which were im- 

 mersed 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 able to absorb, is acted on by 

 yg\nr ^^ ^ 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 

 rstVirff of * grain (.(X)024 mg.) ; yet this sufTiced 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. 



Aggregation of the Protoplasm from the Action of Carbonate of 



