252 E. A. BAUMGARTNER 



of the reptiles are they continuous, nor does the notochord con- 

 tribute in the formation of the hypophysis. Recently these 

 structures were again described as being continuous in pig by 

 Woerdemann ('13) and Miller ('16) and in chick by Atwell ('15). 3 



One turtle embryo shows a cavity in the anterior dilated end 

 of the notochord. Saint Remy found no such cavity in the 

 material he studied and believed that, if such a cavity occurred, 

 it had nothing to do with the formation of a 'Gaumentasche' 

 described by Selenka in oppossum. In the pig, Miller ('16) 

 described a part of the notochord becoming detached from the 

 remainder, migrating anteriorly, and forming the medullary part 

 of the anterior lobe of the hypophysis. This is not the case in 

 reptiles. Saint Remy's 'branche descendante' of the notochord, 

 lying in contact with the entoderm was observed in some turtle 

 embryos. 



A series of drawings to show the shifting of the hypophysis 

 with relation to the notochord and to its position in the body in 

 lizards and alligators was made after the method described in a 

 previous paper for Acanthias ('15). A base line was drawn 

 from the anterior end of the chorda to its axis at the level of the 

 first spinal nerve. The branch of the notochord extending for- 

 ward to the hypophysis probably corresponds to the slightly 

 enlarged anterior bud of the chorda proper as described by Saint- 

 Remy. The anterior end of the bud is one of the points chosen 

 for the base line of the figures. The caudalward shifting of the 

 notochord with relation to the hypophysis may be due, as Saint- 

 Remy stated, to degeneration. This would prove an objection 

 to using it as an end of the base line since the rate of degener- 

 ation probably varies in the different embryos. However, this 

 does not vitiate the general conclusions which may be drawn 

 from the figures. 



The anterior lobe, which at first is ventral to the tip of Rathke's 

 pouch, shifts forward and dorsalward in alligators (fig. 50) , and 

 dorsalward in lizards (fig. 49) until they are on the same hori- 



'* Atwell ('15) has carefully reviewed the literati' re on the relations of the 

 anterior end of the chorda, and has observed an occasional connection between 

 this and Rathke's pouch in rabbits, and a constant connection in the chick. 



