40 



most intimate working of the nucleus the phenomenon in question 

 Tvould hardly be intelligible. - 



Similar experiments with beans and maize were inaugurated later on 

 by Haselhoff/ but he offered calcium and strontium salts together in 

 the beginning and gradually diminished the lime in the culture solu- 

 tion. The plants, however, very probably made use of the occasion to 

 store up a certain amount of lime, which they may have used in the 

 later ]3eriod, and hence his conclusion that a substitution of calcium 

 for strontium salts is possible can not be admitted. 



The writer made an experiment with a phanerogamous plant also. 

 Branches of Iradescantia^ from 12.5 to 12.8 cm. long, were placed in 

 solutions of — 



Per cent. 



(1) Calcium nitrate 0.2 



(2) Strontium nitrate 2 



(3) Calcinm and strontium nitrate, each .1 



At a temperature of 10-15° 0. a decided difference was noticed after 

 twelve days. In the calcium nitrate solution young rootlets 0.5 cm. in 

 length had appeared, but in the strontium nitrate solution only minute 

 knobs were visible. Gradually a difference was also evident between 

 the calcium nitrate and the calcium and strontium nitrate solutions, the 

 root hairs in the former being long and numerous, while in the latter 

 tliey were short and few. However, when the strontium nitrate gradu- 

 ally attained an excess over the calcium salts stored up in the branches, 

 the noxious effect became evident, they having attained a length after 

 forty-two days of only 13 and 13.3 cm., with only two or three leaves 

 on each branch, while those in the solution of calcium nitrate attained 

 a length of 16, 17.2, and 18 cm., with six to seven leaves on each branch. 

 The leaves of the former branches were partially dying, but those of the 

 latter were still healthy. A control case with distilled water demon- 

 strated beyond a doubt that in the case of the strontium nitrate solu- 

 tion the phenomena mentioned were not merely due to the absence of 

 the lime, but to a direct noxious action of the strontium salts. The 

 numerous root hairs which developed in the distilled water further 

 justified the conclusion that lime salts were stored up in the stems. 

 Indeed the writer has demonstrated that besides sulphates, the nodes 

 of the Tradescantia stems have stored up in them nitrates, i)otassium, 

 and magnesium and calcium salts. An undeniable analogy appears to 

 exist, therefore, between the noxious effect of the strontium salts and 

 that of magnesium salts (p. 42), both beginning to be noxious when 

 the amount of lime falls below a certain limit. 



A series of very instructive experiments were recently carried out 

 by U. Susuki^ with five phanerogamous plants — Hordeum, Fagopyrum 

 esculentum, Phlox paniculata, lluhus ida'us, and Coreopsis tinctoria. 

 Some of the plants were watered with a normal solution containing 



iLandw. Jahrb., Vol. XXII, p. 853. ^buU. CoU. of Agr., Tokyo, 1899. 



