RECENT ADVANCES IN SCIENCE 647 



further specimen cut in serial sections by means of which 

 they have been able to check their first account and add certain 

 details to it. Baumgartner has worked out " The Develop- 

 ment of the Hypophysis in Reptiles " (Jour. Morph. Dec. 1916). 

 He finds the epithelial portion arises as a single primordium in 

 turtles, lizards and snakes, and probably alligators. Rathke's 

 pouch appears first, then the two lateral buds, and finally the 

 anterior bud. The three parts of the adult hypophysis are 

 distinct ontogenetically and histologically. 



Some light on the vexed question of lens production in 

 vertebrates is shed by Werber in " On the Blastolytic Origin 

 of the Independent Lenses of some Teratophthalmic Embryos 

 and its Significance for the normal Development of the Lens 

 in Vertebrates " (four. Exper. Zool. Oct. 191 6). He thinks that 

 fully differentiated free lenses found in some teratophthalmic 

 embryos are due to a chemical stimulus of blastolysed potential 

 optic cup substance on any part of the ectoderm with which 

 it may chance to come into contact. 



In the class Avies we have a paper by Riddle on " Sex 

 Control and Known Correlations in Pigeons " (American Nat. 

 vol. 1. July 191 6). A considerable body of evidence exists 

 which points to the fact that germs prospectively of one sex 

 have been forced to produce an adult of the opposite sex. 

 Neither selective fertilisation, differential maturation, nor a 

 selective elimination of ova in the ovary can account for the 

 results obtained. The difference seems to rest on modifiable 

 metabolic levels. 



On the mammalia we have a long series of publications by 

 Thomas, all in the Annals and Magazine of Natural History for 

 191 6. " On the Rats usually included in the Genus Arvi- 

 canthis" (July), " On Rattus as a Generic Name, with a Note 

 on the Nomenclature of Echimys and Loncheres " (ibid.), " On 

 the Generic Names applicable to the Chevrotains ( Tragulidce) ' ' 

 (ibid.) ; " On Small Mammals obtained in Sankuru, South 

 Congo, by Mr. H. Wilson " (Aug.), "On the Generic Names 

 Rattus and Phyllomys " (ibid.), " Three New African Mice of 

 the Genus Dendromus " (ibid.) ; " On the Classification of the 

 Cavies " (Sept.), "Some Notes on the Echimyince " (ibid.), 

 " Two New Argentine Rodents, with a new Sub-genus of 

 Ctenomys (ibid.) ; " Two New Species of Akodon from Argen- 

 tina " (Oct.), " The Grouping of the South American Muridce 



