2IO 



ANIMAL AGGREGATIONS 



SPECIFICITY OF MASS PROTECTION AGAINST COLLOIDAL SILVER 



There are two types of specificity possible: the protective secre- 

 tion may have no other function, and so be specific in that sense; 

 or it may be limited in protection to the species producing it. The 

 first type of specificity will be discussed later. The latter aspect was 

 investigated by placing one animal in a restricted volume of water 

 containing a number of animals of a different species. All our ob- 

 servations show that the protective action of the mass is not limited 



TABLE XXII 



Showing the Non-specificity of the Protection against Colloidal Silver 



Animals 



Many Cladocera, i Asellus 



I Asellus 



Many Cladocera, i Planaria 



I Planaria 



50 Asellus, I Planaria 



1 Planaria 



Desiccated parotid gland, 2 Planaria 



2 Planaria 



Snail slime, 2 Planaria 



2 Planaria 



Snail slime, 2 Planaria 



2 Planaria 



1 Physa, 2 Planaria 



2 Planaria 



Water (Cc.) 



10 

 10 

 10 



Colloidal 

 Silver (Drops) 



10 

 10 



5 

 5 



5 

 5 

 5 

 5 



Time to Death 

 (Hours) 



Over 36 



4-5 

 Over 36 



5-5 

 Over 36 



5-5 

 Over 36 



7-S 



Over 36 

 Less than 18 

 Over 36 

 Less than 16 

 Over 36 



to a given species. This is what would be expected if the fixing of 

 the colloidal silver in some manner is the principal element in the 

 protective action. The results of typical experiments are summa- 

 rized in Tables XXII and XXIII. 



As these tables show, such diverse organisms as Cladocera, Asellus, 

 pond snails, pond leeches, Dendrocadum, and even pond moss, if 

 present in quantity, markedly protect planarians from the toxic 

 action of colloidal silver. Even the actual presence of living organ- 

 isms is unnecessary; snail slime without the snails protects efficiently 

 apparently by adsorbing the colloidal silver. The slime becomes 

 densely colored as the water becomes lighter. Suspensions in 

 water of desiccated parotid glands of sheep exhibit similar adsorptive 

 phenomena and have similar protective value. 



