222 THE THEORY OF EVOLUTION 



as formerly, laid its eggs in the water, but transferred 

 the development of the germ to its interior. Since 

 the albumen, the egg skin, the lime shell are all deposited 

 by glands and these are situated in the oviduct, in 

 the oviduct alone could these glands be arranged as 

 an absolutely necessary condition for the formation 

 of the covers and therewith the newly adapted form 

 of development of the germlets (Keimlinge). The 

 formation of the glands is furthermore in that case 

 only a purposely adapted means for the new embryogeny 

 when the egg had been previously fertilized in the 

 uterus or oviduct. There were consequently, at the 

 time when that adaptation occurred, males and females, 

 and the seminal cells were introduced by pairing into 

 the genital apparatus of the female. In brief, the 

 birds were at the time of that hypothetical adaptation 

 the same as now. They had, however, teeth in the 

 beaks and also perhaps (all ?) a longer tail : there 

 are some points of support for this in palaeontology 

 and embryogeny. 



Among the Mammals we arrive at similar stages 

 which, according to their entire nature, must be ac- 

 cepted only as adaptations of the embryonic life itself 

 and that in the uterus of a mammal, unless it be assumed 

 that the ancestors of the Mammals formerly lived as 

 grown-up individuals in the interior of the maternal 

 body. What, then, were these mothers ? 



In short for the case that in a general way the 

 embryogeny of the Mammals and Birds was not always 

 the same as to-day the development of the germ of 



