Livingston : Chemical stimulation of a green alga 31 



and Heald "^ worked upon Lttpums, Pisiim and Zea radicles, 

 finding an acceleration in case of the cations H, Cu, Ni, Co and 

 Ag. Kahlenberg and Austin f determined the concentration of 

 ionic H which can be borne by seedlings of Lupinus when their 

 roots are in solutions of acid sodium salts. Coupin \ made 

 determinations of the effect of solutions of salts of Na, K, and NH^ 

 upon wheat seedlings. Kanda § worked with Pistini and Vicia 

 seedlings and with CuSO^ and ZnSO^. Studies on the toxicity 

 of a number of acids and their Ca and K salts upon wheat, clover, 

 and maize, were made by Cameron and Breazeale.!] True and 

 Gies \ have recently carried out what is probably now the most satis- 

 factory research we have on this subject. They determined for 



i pi mis 



Ao-. Hff. Zn. Na. K. Ca and M^. F. A 



upon the effect of H and OH ions on Zea seedlings, and Dandenoff 

 has just published a paper on experiments in this line with seedlings 

 of Zea, LiLpimis^ and Pisum. The latter author made determina- 

 tions of the neutralizing power of seedling roots in toxic solutions, 

 which appears to be a very important consideration and one which 

 seems not to have been attacked before. This author demon- 

 strates also, what had already been described by True and 

 Oglevee^l that the presence of insoluble bodies has an influence 

 upon the physiological effect of salt solutions. This is the phe- 



* Heald, F. de F. On the toxic effect of dilute solutions of acids and salts upon 

 plants. Bot. Gaz. 22: 125-153. 1896. 



•(- Kahlenberg, L, & Austin, R. W. The action of acid sodium salts on Liipimts 

 albus. Jour, Phys. Chem. 4 : 553-569. 1900. 



X Coupin, H. Sur la toxicity des composes du sodium, du potassium, et de I'am- 

 raonium ^ regard desv^g^taux superienrs. Rev. Gen. Bot. 12; 177-194- IS<^^' 



\ Kanda, M. Studien uberdie Reizwirkung einiger Metallsalze auf das Wachs- 

 thum hoherer Pflanzen. Jour. Coll. Sci, Imp. Univ. Tokyo ig^^: 1-37- I9°4' 



Cameron, F. K. & Breazeale, J, F. The toxic action of acids and salts on 



seedlings. Jour, Phys. Chem. 8 : I-13. 1904. 



^True, R. H. & Gies, W. J. On the physiological action of some of the heavy 



metals in mixed solutions. Bull. Torrey Club 30 : 390-402. 1903. 



** Loew, F. A. The toxic effect of H and OH ions on seedlings of Indian corn. 



Science II. 18 : 304-308. 1903. 



ttDandeno, J. B. The relation of mass action and physical affinity to toxicity. 



Am. Jour. Sci. IV. 17: 437-458. 1904. 



tJTrue, R. H. & Oglevee, C. S, The effect of the presence of insoluble sub- 

 stances on the toxic action of poisons. Science II. 19 : 421-424. I904. — Also Bot. 

 Gaz. 39 : 1-21. 1905. 



