Livingston ; Chemical stimulation of a green alga 15 



5;//io,ooo, with some acceleration of zoospore production in ;//i,- 

 ooo to 5;//io,ooo. The acceleration is not as marked as in most 

 of the other salts, however. Normal growth occurs in ;//io,ooo 

 and weaker solutions, 



77. Lithinni sulfate {yk^O^. — A thorough test of this salt 

 was not made, but as far as the experiments were carried the re- 

 sults agree well with the data given for the nitrate. 



18, Magneshun nit7'ate ^^i^O^^, — This cation is present in 

 the nutrient medium. The experiments consisted in increasing 

 its amount. 5/2/100 does not kill, but produces the palmellaform 

 as does also nlioo and, to some extent, ^njiooo. Zoospore 



1 



'■I 



/p. Magiiesiwn sitlfate {y[gSO^. — This salt agrees with the 

 nitrate perfectly excepting that it was impossible to establish a 

 true zoospore acceleration here. Sometimes this phenomenon 

 appears and at other times not It appeared most often at njioo 

 concentration. Perhaps undissociated molecules have to do with 

 this response, but no particular study was made here, this subject 

 lying rather in the field of nutrient salts than in that of toxic ions. 



Nickel nitrate (K\(^OX\ — A 



produces death. 



■■} 



practically all of the cells being of the other form, but in ;//i 00,000 

 there is about an even mixture of the two forms. A rather slightly 

 marked zoospore acceleration occurs In ;/y'ioo,ooo, and still less 

 marked in weaker solutions. At a concentration of ;//io,ooo»ooo 

 the alga is certainly uninfluenced by the poison. The zoospore 

 acceleration grades almost imperceptibly into the normal produc- 

 tion of these bodies, 



21. Potassium ?n trate (¥iNO^. — This salt is so common in 

 the environment of plants that it would hardly be expected to 

 produce very marked stimulation responses. It is probably less 

 toxic toward plants in general than any other salt. At a concen- 



Snf 



is produced. This is perhaps 



due, in part at least, to osmotic phenomena. No acceleration of 

 zoospore production was observed. 



22. Potassium sulfate (K^SOJ. — As far as could be deter- 

 mined, this salt acts exactly like the nitrate. 



