34 MAMMAKV APPARATUS OP THE MAMMALIA 



blunders. Their suggestive power was so 

 great that such eminent investigators as 

 Gegenbaur and Ruge did not doubt the cor- 

 rectness of Owen's statements, even tliough 

 they could find in their own specimens only 

 insignificant remains of the incubatorium, or 

 trifling depressions of the gland areas. And it 

 produced such an effect upon Kiaatsch that he 

 fell into the error of describing the different 

 involutionary and evolutionary conditions of 

 the incubatorium in the pauses between the 

 periods of pregnancy as mammary pouches, 

 although the prepared material lying before 

 him was not cut up like the Echidna specimen 

 of Owen. I have had the opportunity myself 

 of studying Klaatsch's interesting material 

 again, and have been able to demonstrate that 

 the supposed mammary pouches are simply 

 parts of the incubatorium more or less reduced. 

 If we now proceed to draw the phylogenetic 

 conclusions from the facts we have gained from 

 the consideration of the ontogenesis, our point 

 of departure is the established fact that the 

 development of the mammary apparatus does 

 not start with arrangements for the accommoda- 

 tion of the young— that is, with mammary 



