564 SCIENCE PROGRESS 



Other papers include : 



Gilchrist, " Plancto-thuria diaphana, g. et sp. n." {Quart. Jour. Micro. Sci., 

 vol. Ixiv, no. 3, March 1920) ; and Heilbrunn, " An Experimental Study of 

 Cell-division, i, The Physical Conditions which determine the Appearance 

 of the Spindle in Sea-urchin Eggs " {Jour. Exp. ZooL, vol. xxx, no. 2, Feb. 

 1920) ; Edmonson, " The Reformation of the Crystalline Style In My a 

 arenaria after Extraction " {Jour. Exp. Zool., vol. xxx, no. 3, April 1920) ; 

 Heilbrunn, " Studies in Artificial Parthenogenesis. Ill, Cortical Change and 

 the Initiation of Maturation in the Egg of Cumingia " {Biol. Bull., vol. xxxviii, 

 no. 5, May 1920) ; Latchford, " Canadian Sphaeridae " {Canadian Field Nat., 

 vol. xxxiv, nos. 2 and 4, Feb. and April 1920) ; and McLearn, " Three New 

 Pelecypods from the Coloradoan of the Peace and Smoky Valleys, Alta " 

 {ibid., no. 3, March 1920). 



Gatenby has continued his series of papers on " The 

 Cytoplasmic Inclusions of the Germ-cells. Part VI, On the 

 Origin and Probable Constitution of the Germ-cell Determinant 

 of Apanteles glomeratus, with a Note on the Secondary Nuclei " 

 {Quart. Jour. Micro. Sci., vol. Ixiv, part 2, Jan. 1920). This 

 determinant is almost entirely composed of an albuminous 

 proteid, very dense and definitely basophil, and it is partly in 

 the form of fine granules. It is not soluble in solvents that 

 disintegrate yolk spheres, nor does it appear to contain fat or 

 glycogen, and it is not destroyed by the fixations that remove 

 the mitochondria. It takes origin as a concentrated area at 

 the posterior pole of the young oocyte, at first simply denser 

 than the surrounding protoplasm, but later more clearly marked 

 off. With " Some Habit Responses of the large Water-strider, 

 Gerris remigis, Say. Ill " (Anier. Nat., vol. liv, Jan. 1920), 

 Riley concludes a series of investigations on the behaviour of this 

 and other allied forms. They respond more readily to moving 

 variations in light intensity than they do to stationary ones, 

 and possibly also to variations in the moisture content of the 

 atmosphere. The Gerrids being mainly apterous forms, were 

 unable to migrate by flight, and so their actions were more 

 easily observed. Apparently in finding their way back to a 

 pool from which they had been moved, or in migrating to 

 another pool when the one they are inhabiting dries up or 

 becomes foul, they are mainly guided by the sense of sight, 

 although moisture also may play a subsidiary part. 



Other papers include : 



Doncaster and Cannon, " On the Spermatogenesis of the Louse {Pediculus 

 corporis and P. capitis), with some Observations on the Maturation of the 

 Egg " {Quart. Jour. Micro. Sci., vol. Ixiv, pt. 3, March 1920) ; Ewing, " A 

 Gamasid Mite annoying to Man " {Jour. Parasit., vol. vi, no. 4, June 1920) ; 

 Leon, " Quelques Observations sur les Pediculides" {ibid., no. 3, Mar. 1920) ; 

 Mclndoo, " The Olfactory Sense of Orthoptera " {Jour. Comp. Neur.^ vol. xxxi, 

 no. 5, June 1920) ; Shaffer, " The Germ-cells of Cicada {Tibicen) septemdecim " 

 {Biol. Bull., vol. xxxviii, no. 6, June 1920) ; Weidman, " Variation of the 



