2 MAMMARY APPARATUS OF THE MAMMALIA 



criticism. They have all failed because of the 

 discrepancies between theory and facts which 

 come to light when one follows these specula- 

 tions to their logical conclusion. 



So to-day, taking into consideration all the 

 unsuccessful attempts, some authors have main- 

 tained that the phylogeny of the mammary 

 apparatus is still unexplained. It seemed im- 

 possible to answer either the question, how the 

 Mammals came into the possession of this 

 apparatus, so necessary for the bringing up of 

 their offspring, or the question, what changes 

 have modified the mammary organs in the 

 various orders of Mammals. 



Still, such a pessimistic outlook is not justified. 

 Far-reaching problems like these can only be 

 solved after investigations on a vast material 

 embracing every possible stage and every 

 possible family of Mammalia. For years, it has 

 been my endeavour to bring together such a 

 collection, and the completer it became, the 

 clearer became my conviction that a solution 

 was obtainable. Now that I have finished my 

 work, I hope that my results will afford some 

 explanation of these baflfling problems. In 

 dealing with my subject, I propose to describe 



