PROTECTION FROM TOXIC REAGENTS 



209 



secretion in the sea-water, protecting animals from the action of 

 the colloidal silver; nor is there evidence for the presence of an 

 active autodestructive agent, which Drzewina and Bohn also postu- 

 lated to explain certain cases in which the greater mass of animals 

 exposed to KCl die more rapidly than do the solitary individuals. 

 In the presence of an active autodestructive secretion one would 

 expect the mass to die more rapidly than do the isolated individuals, 



which is not the case. 



TABLE XXI 



Showing Righting Time of Ophioderma after an Exposure of 19 Hours in 

 Twice-Reconditioned and in Fresh Suspensions 



* One failed to give the righting reaction. 



There is good evidence that the secretion of slime or other or- 

 ganic matter into the suspension does remove the colloidal silver 

 and so render the solution less toxic. It is particularly significant 

 that, after having been twice used, the suspension required as much 

 colloidal silver as was used in a fresh suspension to bring it to the 

 same color. Similar results were obtained from other experiments. 



More recent experiments in this laboratory, the results of which 

 are unpublished as yet, show clearly that groups of goldfish live 

 longer in a given volume of a given concentration of colloidal silver 

 than do isolated goldfishes similarly isolated into the same amount 

 of the same concentration of colloidal silver suspension; and that, 

 under these conditions, the group removes significantly more silver 

 from suspension than do the isolated individuals. The experiments 

 do not yet show conclusively whether this will account for all of 

 the observed group protection. 



