390 SCIENCE PROGRESS 



Other papers include : 



Stebbing, " Some Crustacea of Natal " {Ann. Durban Mus., vol. iii, Jan. 

 1921) ; Johansen, " The Larger Freshwater Crustacea from Canada and 

 Alaska " {Canad. Field Natur., vol. xxxv, Feb. 192 1) ; Copeman, " Note on the 

 Capture (in London) of a Rare Parasitic Fly, Hammomyia [Hylephila) unilineata 

 Zett." {Proc. Zool. Soc, pt. i, March 1921) ; Hess, " Tracheation of the Light- 

 organs of some Common Lampyridse " [Anat. Rec, vol. 20, No. 2, Jan. 192 1) ; 

 Ito, " On the Metamorphosis of the Malpighian Tubes of Bombyx mori L." 

 {Journ. Morph., vol. 35, No. i, March 12, 1921) ; Metz, and Nonidez, " Sperma- 

 togenesis in the Fly^si/MS sericeus, Say." {Journ. Exper. Zool., vol. 32, No. i, 

 Jan. 1921) ; and Plough, " Further Studies on the Effect of Temperature on 

 Crossing Over " {ibid.. No. 2, Feb. 1921) ; Burge and Burge, " An Explanation 

 for the Variation in the Intensity of Oxidation in the Life Cycle " {ibid.. No. 

 2, Feb. 1921) ; Johannsen, " The First Instar of Wohljahrtia vigil. Walker " 

 {Journ. Parasit,, vol. vii, March 1921) ; Bodine, " Factors Influencing the 

 Water Content and the Rate of Metabolism of Certain Orthoptera "{Journ. 

 Exper. Zool., vol. 32, No. i, Jan. 1921). 



Vertebrata.< — Herrick has dealt fully with the question of 

 " The Origin of the Cerebral Hemispheres " {Journ. Comp. Neur., 

 vol. 32, No. 4, Feb. 1921). The telencephalon is probably the 

 front part of the ancestral vertebrata whose walls are not com- 

 plicated by thickening. This, in certain low forms, has become 

 thickened and specialised in two places ; the first, as a thickened 

 outgrowth in the region of the lamina terminalis, forms the 

 olfactory lobe, and the second is thickened without evagination. 

 Only the evaginated portions are to be looked on as the hemi- 

 spheres, and in all vertebrates these two subdivisions of the 

 telencephalon can be made out. Certain generalised fishes have 

 thin-walled hemispheres, a form which may have been adapted 

 to oxygenate the brain. With the transition to the Amphibia 

 and its consequent oxygenated blood supply it was possible for 

 the evaginated hemispheres to evolve progressively. 



Other papers include : 



Hyman, " The Metabolic Gradients of Vertebrate Embryos. Teleost 

 Embryos " {Biol. Bull., vol. 40, No. i, Jan. 1921) ; Okkelberg, " The Early 

 History of the Germ-cells in the Brook-lamprey, Entosphenus wilderi (Gage), 

 up to and including the Period of Sex Differentiation " {Journ. Morph., vol. 

 35, No. I, March 1921) ; Regan, " Three New Fishes from South Africa, col- 

 lected by Mr. H. W. Bell Marley " {Ann. Durban Mus., vol. iii, Jan. 192 1) ; 

 and Stockard, " Developmental Rate and Structural Expression : An Experi- 

 mental Study of Twins, ' Double Monsters,' and Single Deformities, and 

 the Interaction among Embryonic Organs during their Origin and Develop- 

 ment " {Amer. Journ. Anat., vol. 28, No. 2, Jan. 1921). 



Baitsell, " A Study of the Development of Connective Tissue in the 

 Amphibia" {Amer. Journ. Anat., vol. 28, No. 3, March 1921) ; Boulenger, 

 " Experiments on Colour-changes of the Spotted Salamander {Salamandra 

 maculosa) conducted in the Society's Gardens " {Proc. Zool. Soc, pt. i, 

 March 1921) ; Harrison, " On Relations of Symmetry in Transplanted 

 Limbs " {Journ. Exp. Zool., vol. 32, No. i, Jan. 1921) ; Jaesch, " Beobach- 

 tungen iiber das Auskriechen der Larven von Rana arvalis und fusca und die 

 Function des Stirndrusenstreifens " {Anat. Am., bd. 53, March 192 1) ; 



