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THE AMERICAN NATURALIST [Vol. XLVI 



In Shorthorn cattle, classes 4, 5 and 7 of this table are 

 not met with, neither are conditions parallel to class 4 

 ever observed in any other mammals. The further expla- 

 nation may be as follows : Reaction between W and R does 

 not begin until an excess of W is present (a condition not 

 hard to parallel in the chemical laboratory) but when 

 reaction does begin it is quite rapid, destroying all of R 

 and most likely leaving an excess of W at the point of 

 first attack. This would eliminate Class 4 (type 3 of 

 the series previously described) and Class 5 (pure 

 albinos) of this table. There may be "albino" cattle; 



