10 Livingston : Chemical stimulation of a green alga 



the filamentous form from which it came, and several dead cells 

 with granular remains of others.) 



j. Ammonium nitrate (NH 4 NO a ). — The killing strength was 

 not determined ; it lies above u ' 100. In the last named concentra- 

 tion a large proportion of the cells die, the remainder becoming 

 palmella. The same is true of // 1,000 but more cells live. (See 

 fig. 6, showing palmella cells arising from cylindrical filamentous 

 ones, by the survival of the most resistant, apparently.) In 5/// 



^#®g 





FIGURE 6. Palmella and dead cells from ;/ 1,000 XH,NO.,. 



Figure 7. Palmella, traces of filaments, sporangia, and zoospores, from 

 5«/lo,coo (NH + ),S0 4 . 



10,000 and 6nj 1 0,000, the palmella form is still more or less 

 apparent, though good filaments usually persist. There is in the 

 last named strengths an acceleration of zoospore production, as 

 in the aluminium salts. At ;//io,ooo all traces of palmella form 

 are lost and the zoospore activity has sunk to normal, i. e., this 

 strength gives the usual growth for a solution of low osmotic 

 pressure. 



