RECENT ADVANCES IN SCIENCE 567 



Bifida Defect " [Jour. Exp. Zool., vol. xxx, no. 2, Feb. 1920) ; Rice, " The 

 Development of the Skull in the Skink, Emueces quinquelineatus L, I, The 

 Chondrocranium " {Jour. Morph., vol. xxxiv, no. i, June 1920) ; Pohlman, 

 " A Consideration of the Branchial Arcades in the Chick, based on the 

 Anomalous Persistence of the 4th Left Arch in a Sixteen-day Stage " {Anat. 

 Rec, vol. xviii, no. 2, March 1920). 



" The Origin, Growth, and Fate of Osteoclasts, and their 

 Relation to Bone Resorbtion " forms the subject of a paper by 

 Arey [Amer. Jour. Anat., vol. xxvi, no. 3, Jan. 1920). He 

 concludes that the multinucleate giant cells usually termed 

 osteoclasts include elements morphologically similar but never- 

 theless developmentally distinct. Osteoclasts appear to arise 

 from the confluence of mesenchymal cells and the connective 

 tissue of marrow, but their chief source is from the old osteoblasts 

 and bone cells. They undergo retrograde changes and ulti- 

 mately disappear. Only indirect and insufficient evidence 

 points to osteoclasts as active agents of bone resorbtion, and 

 it is probably better to regard them as degenerating and fused 

 osteoblasts. 



Other papers include : 



Addison, "Histological Study of the Spleen of the Rabbit under Heightened 

 Phagocytic Activity" {Amer. Jour. Anat., vol. xxvi, no. 3, Jan. 1920) ; 

 Adelmann, " An extreme Case of Spina Bifida with Dorsal Hernia in a Calf " 

 {Anat. Rec, vol. xix, no. i, June 1920); Anthony, "New Rodents and 

 New Bats from Neotropical Regions " {Jour. Mammal., vol. i, no. 2, Feb. 

 1920) ; Asami, " Observations on the Follicular Atresia in the Rabbit's 

 Ovary " {Anat. Rec, vol. xviii, no. 4, May 1920) ; Badertscher, " Eosinophilic 

 Leucocytes in the Thymus of Postnatal Pigs " {ibid., no. i, 1920) ; Baum- 

 gartner, Nelsen, and Dock, "Development of the Uterine Glands in Man" 

 {Amer. Jour. Anat., vol. xxvii, no. 2, May 1920) ; Beckwith, " Note on a 

 Peculiar Pancreatic Bladder in the Cat" {Anat. Rec, vol. xviii, no. 4, May 1920); 

 Bowles, " The California Grey Squirrel an Enemy to the Douglas Fir " 

 {Amer. Forest., vol. xxvi, Jan. 1920) ; Congdon, " The Distribution and 

 Mode of Origin of Septa and Walls of the Sphenoid Sinus " {Anat. Rec, 

 vol. xviii, no. 2, March 1920) ; Cooper, " A Case of the Inferior Vena Cava 

 uniting with the Azygos Vein in the Dog " {ibid., vol. xvii, no. 5, Jan. 1920) ; 

 Craigie, " On the Relative Vascularity of Various Parts of the Central Nervous 

 System of the Albino Rat " {Jour. Comp. Neur., vol. xxxi, no. 5, June 1920) ; 

 Draper, " The Prenatal Growth of the Guinea-pig " {Anat. Rec, vol. xviii, 

 no. 4, May 1920) ; Hanna, " Mammals of the St. Matthew Islands, Bering 

 Sea " {Jour. Mam., vol. i, no. 3, May 1920) ; Hanson, " The Development 

 of the Shoulder-girdle of Sus Scrofa " {Anat. Rec, vol. xviii, no. i, Feb. 1920) ; 

 Hausmann, " The Microscopic Identification of Commercial Fur Hairs " 

 {Sci. Month., Jan. 1920) ; Hinton, " The Subspecies of Paraxus flavivittis, 

 Peters " and " Three New Species of Spalax monticola " (both in Ann. and 

 Mag. Nat. Hist., March 1920) ; Hollister, " Two New East African Primates " 

 {Smithsonian Misc. Coll., vol. Ixxii, no. 2, Jan. 1920) ; Hornaday, " The 

 Birth of a Pigmy Hippopotamus " {Zool. Soc Bull., vol. xxiii, no. i, Jan. 

 1920) ; Horsley, " A Description of a Six-legged Dog " {Anat. Rec, vol. xix, 

 no. I, June 1920) ; Howell, A. B., " A Study of the California Jumping Mice of 

 the Genus Zapus " {Univ. Cal. Pub. Zool., vol. xxi, no. 5, May 1920) ; Howell, 

 A. H., " A New Race of the Florida Water-rat " {Jour. Mamm., vol, i. 



