16 



Livingston ; Chemical stimulation of a green alga 



If ate 



The plant is killed by n\\oo 



and to some extent by 5«/i,ooo. In 5«/i,ooo and nji,ooo the 

 palmella form is produced, with few or no zoospores, and the cul- 

 ture becomes normal at «/ 10,000. No acceleration of zoospore 



production occurs here. 



2^. Silver nitrate (AgNO^). 



Death 



from ;// 



'/ 



Filaments do not appear in 7// r ,000,000, but 

 5 «/ 1 0,000, boo, where also there is an increase 



16 



a 



17 



Figure 16. Palmella and filaments from 5h/io,ooo,ooo AgNOg. 



Figure 17. Normal filaments and zoosporangia (a), from m/io,ooo,ooo AgNOj. 



in the number of zoospores. The cultures are normal or slightly 



6 



'I 



A 



//. The former shows typical palmella form in 



w/i, 000.000, the second a mixture of palmella and filamentous 



5 



^/ 



) The limits are 



quite sharply defined for this salt. 



2§. Sodium nitrate (NaN03). — This cation is but little more 

 poisonous than potassium. The palmella form is produced in 



