48 PHYSIOLOGICAL ROLE OF MINERAL NUTRIENTS. 



in the later period, 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 Tradescantia 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) Calcium and strontium nitrate, each 1 



At a temperature of 10-15° C. 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 they were short and few. Moreover, when the strontium 

 nitrate gradually 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 par- 

 tially dying, but those of the latter were still healthy. A control case 

 with distilled water demonstrated beyond a doubt that in the case of 

 the strontium nitrate solution 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, potassium, 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, both begin- 

 ning to be noxious when the amount of lime falls below a certain limit. 

 A series of very instructive experiments were carried out by IT. 

 Suzuki a with five phanerogamous plants — Hordeum, Fagopyrmn escu- 

 lentum, Phlox paniculata* Muhus idaeus, and Coreopsis tinctoria. Some 

 of the plants were watered with a normal solution containing calcium 

 in the form of calcium nitrate, and others with solutions in which the 

 calcium nitrate was replaced by equivalent quantities of strontium 

 nitrate and of barium nitrate. Only the plants in the normal solutions 

 showed a strong and vigorous development, while those in the barium 

 and strontium solutions exhibited gradually an injurious action. 



"Bull. Coll. of Agr., Tokyo, 1900, Vol. IV, No. 1, "Can strontium and barium 

 replace calcium in jibanerogams?" 



