SUMMARY OF CURRENT RESEARCHES 



KKLATINH TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryolog-y.f 



Development of Mammalian Pituitary Body.J — P. T. Herring 

 has studied this in the cat and other mammals. In the cat the posterior 

 lobe of the pituitary body remains hollow throughout development, 

 whereas in most of the mammals that have been studied in tills con- 

 nection the posterior lobe becomes a solid structure at a comparatively 

 early stage. 



The epithelial portion is derived entirely from the ectodermic wall of 

 the buccal invagination known as Ratke's pouch. Its origin is single 

 and mesial. The epithelium is differentiated at an early stage into two 

 parts, which show differences in arrangement, structure, and vascularity. 

 One of these, the pars intermedia, is closely adherent to the wall of the 

 cerebral vesicle from its earliest appearance, and remains in intimate 

 association with it. The other portion of buccal epithelium gives rise 

 to the anterior lobe proper. The lower portion of Ratke's pouch, which 

 is not adherent to the brain, forms a solid mass of cells which grow into 

 surrounding blood-channels and into the cavity of the pouch itself. 

 The original cavity of Ratke's pouch persists as a narrow cleft separating 

 the anterior lobe proper from the epithelial portion of the posterior lobe. 



The infmidibnlum is an invagination of part of the wall of the 

 thalamencephalon which is adherent to the anterior and upper wall of 

 Ratke's pouch. It therefore possesses an epithelial covering derived 

 from the latter. The infundibular process grows backwards, and, in 

 the cat, retains its central cavity. It is lined by ependyma cells which 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



\ Quart. Journ. Exp. Physiol. , i. (1908) pp. 163-85 (11 figs.). 



