482 



Trans. Acad. Sci. of iSt. Louis. 



dicate a series for the acids, some of the factors being more 

 closely related. 



While the above arrangement of the results should be pre- 

 sented, it is evident from a glance at the tables that an 

 arrangement whereby the acid portion of the molecules might 

 be more readily comparable would be of greater interest ; and 

 this arrangement is shown in Tables V and VI. In these the 



Table V. 



data are furnished for each alga, and the averages are also 

 given. The results are now strikingly evident. In each case 

 where an ammonium compound of the acid is employed it 

 shows the highest toxic value, and, in general, it is a toxic 

 value which approaches that of acids, or salts of the heavy 

 metals, although this latter point is not demonstrated in the 



