Livingston : Chemical stimulation ok a <;reen alga 13 



12. Hydrogen nitrate, nitric acid (HNO^). — This body kills 

 the plant at a concentration of 5»/ 10,000. Palmella is produced 

 from 11 j '10,000 to 611 100,000, sometimes even in 3^/1 00,000. 

 Acceleration of zoospore production is exhibited from n\\ 00,000 

 to 6nj 1 00,000 or 3;// 100,000, in certain cases, and below the last- 

 named strength, at least at n\ 100,000, the alga appears normal. 

 (See Jig. ij, which shows palmella produced from filaments in a 

 solution of 6///ioo,ooo concentration.) 



CuS0 4 . 



Figure 12. Palmella and some filaments changing to palmella, from w/i, 000,000 



\ 



Figure 13. Palmella from 6w/ioo,ooo HN0 3 . 



13. Hydrogen sulfate, sulfuric acid (H 2 S0 4 ). — This follows 

 nitric acid very closely. There seems to be here sometimes a 

 tendency for the palmella range to extend downward so to include 

 «/ioo,000, but it was impossible to establish this for a certainty in 

 all series. If it be so, it of course means that the sulfate is some- 

 what more active than the nitrate, and that the action in this case is 



