270. E. A. BAUMGARTNER 



cords. In a 28 mm. Aromochelys embryo, differentiation is 

 possibly just beginning. 



From a study of my material it appears that Valenti has 

 over-emphasized the distinction in staining reaction of ectoderm 

 and entoderm in reptiles. The cells appear similar in shape 

 and arrangement. Very early, the cells of the hypophyseal an- 

 lage are columnar and stain more darkly than either ectoderm 

 or entoderm. It would appear difficult from histological char- 

 acteristics to exclude the entoderm from taking part in the for- 

 mation of the hypophysis. 



Glands. As has been described by other investigators, in all 

 of the specimens examined glandular outgrowths appear, first, 

 from the wall of the anterior lobe. But this outgrowth is from 

 all sides of the lobe, not from the anterior wall only, as Herring 

 ('08) found in mammals. In very young turtle embryos one or 

 two projections, caudo-dorsal to the stalk, are probably glandu- 

 lar outgrowths and may correspond to Woerdemann's ('14) 

 'solider Auswuchs' which this author thinks is of special impor- 

 tance. In alligators 22 mm. in length there are a great many 

 evaginations from the cerebral side of the anterior lobe, though 

 there is only one long, caudally-projecting outgrowth from the 

 lower surface. In alligators many of these outgrowths show a 

 distinct lumen. In other forms they are usually solid, with 

 only slight extension of the main lumen into them. In snake 

 embryos 10 cm. long, the glands occasionally show a lumen or 

 a central cytoplasmic zone near their free ends. In alligators, 

 at least, the glandular outgrowths seem to be evaginations from 

 the hypophyseal wall, with lumina extending into them, and not 

 solid cords formed by the breaking up of a very much thickened 

 wall as Joris ('07) described in mammals. These evaginations 

 may later become solid cords. However, since the lateral buds 

 become solid very early, cords are probably formed by the 

 breaking up of their walls or as outgrowths from them. The 

 hollow pars intermedia of a 10 cm. snake shows no cords, while 

 the solid pars intermedia of a 12 cm. Eutaenia sirtalis has several 

 cord-like extensions. 



