572 SCIENCE PROGRESS 



Parts III and IV) a paper on the " Early Development and 

 Placentation in Arvicola [Microtus) amphibius, with Special 

 Reference to the Origin of Placental Giant Cells." The develop- 

 ment of Microtus amphibius is of the excentric type, agreeing 

 in general outlines with that of the mouse and rat. Phagocytic 

 giant cells arise from endothelial cells of the maternal capil- 

 laries which surround the implantation cavity at an early 

 stage. All the placental giant cells have the same maternal 

 endothelial origin. The penetration of the ectoplacental 

 trophoblast is assisted by the giant cells which destroy the 

 decidual tissue in its line of advance. 



" The Relative Distribution of Clasmatocytes in the Various 

 Organs of the Seven-day-chick Embryo " is the subject of 

 a paper by C. S. Beck {Anat. Rec, vol. xxiv, No. 2, Sept. 1922). 

 Clasmatocytes occur in considerable numbers in all those 

 structures of the embryo which contain loose reticular mesen- 

 chyme, their numbers apparently varying according to the 

 amount of that tissue present. " The brain, excluding the 

 optic lobes and retina, is the only structure supposedly con- 

 taining no loose reticular mesenchyme in which clasmatocytes 

 are found." 



T. Pehrson contributes " Some Points in the Cranial De- 

 velopment of Teleostomian Fishes " to Acta Zoologica, No. i, 

 1922. This paper deals with the development of the primordial 

 cranium of Amia calva and the development of the bones 

 related to the sensory canals. In discussing the general 

 results of this work, the writer points out that certain features 

 such as the 'presence of independent supra-orbital cartilages 

 and the development of a frontal foramen epiphyseos, point 

 to primitive relations in Amia. 



Of importance, also, are the following papers : 



Janosik, J., " Explication des diverses formes et de la position des reins," 



Archiv de Biol., vol. xxxii. No. 3, 1922. 

 Janosik, J., " Le developpement de la rate et ses relations avec la ' Bursa 



Omentalis,' " Archiv de Biol., vol. xxxii, No. 3, 1922. 

 Salazar, a. L., " Sur la forme de d6g6nerescence des follicules anovulaires 



de Regnaud et d'autres reliquats provenant des cordons ovig^nes de 



I'ovaire de la lapine," Anat. Rec, vol. xxiv, No. 2, Sept. 1922. 



Invertebrate Morphology (excluding Entomology). — In a 

 paper " On some Scottish Oligochaeta, with a Note on Encyst- 

 ment in a Common Freshwater Oligochaete, Lumbriculus 

 variegatus (Miill) {Trans. Roy. Soc. Edin., vol. liii. Part II, 

 No. 14), J. Stephenson describes two new forms and records 

 the presence of certain species which have not hitherto been 

 found in the British Isles. Of the new species, Vejdovskyella 

 comata (Vejd.), var. scotica was taken from a pond on a hill 

 above Ascog, Bute, while the other, Tubifex {Peloscolex) insularis, 



