PROTECTION FROM TOXIC REAGENTS 



203 



of confining many animals within a small space, may easily be 

 demonstrated even here. With the Ophioderma, for example, if the 

 glass finger bowls were covered with glass plates during the exposure 

 to colloidal silver, thus stopping free gaseous exchange, the grouped 

 animals were in much worse condition than were their isolated 

 fellows. 



A priori, one would expect exactly such a result, since in each 

 case there is much less of the toxic substance present per individual 



TABLE XVIII 



Showing the Results of Exposure to Suspensions of Colloidal Silver 

 Followed by Transfer to Water Similar to That to 

 Which the Animals Were Accustomed 

 All were run at room temperature. 



composing the larger groups than when from i to 3 animals are 

 placed in the same amount of the same concentration of toxic sub- 

 stance (Pieron, 1921). Drzewina and Bohn consider this possibility 

 (1921C, 1928) and dismiss it as inadequate because of their experi- 

 ments upon the effect of reconditioned toxic solutions and upon the 

 relation of volume of the toxic material to its effect upon exposed 

 animals. They summarize their conclusions repeatedly in some 

 such words as the following (1921J): 



