RECENT ADVANCES IN SCIENCE . 565 



Ovum (Sarcoptes scahiei) under Cover-glass Pressure" {Joiiy.Parasit., vol. vi, 

 no. 3, March 1920) ; and Yuasa, " The Anatomy of the Head and Mouth Parts 

 of Orthoptera and Euplexoptera" {Jour. Morph., vol. xxxiii.no. 2, March 1920). 



Jordan has added a further paper to his series on " Studies 

 on Striped Muscle Structure. VI, The Comparative Histology 

 of the Leg and Wing Muscle of the Wasp, with Special Reference 

 to the Phenomenon of Stripe Reversal during Contraction, and 

 to the Genetic Relation between Contraction Bands and Inter- 

 callated Discs " {Amer. Jour. Anat., vol. xxvii, no. i, March 1920). 

 " Contraction in striped muscle is associated with a genuine 

 reversal of striations as regards a deeply staining substance of 

 the dark disc of the sarco-style. This reversal of striations 

 results in the formation of contraction bands in the contracted 

 fibre." The beaded condition of the fibre is an artifact, and 

 not the result of contraction. Anisotropy and the deep staining 

 character of the dark disc are distinct phenomena, and reversal 

 of striations concerns only the deeply staining substance of 

 the dark disc. The contraction band is a new structure, and 

 not an optical illusion, and the simplest type of intercallated 

 disc is identical with this band. 



Other papers include : 



Bridges, " White-ocelli— an Example of a Slight Mutant Character of 

 Normal Viability " (Biol. Bull., vol. xxxviii, no. 4, April 1920) ; Hyman, 

 " The Development of Gelasimus after Hatching " (Jour. Morph., vol. xxxiii, 

 no. 2, March 1920) ; MacDowell, " Bristle Inheritance in Drosophila. III. 

 Correlation " (Jour. Exp. ZooL, vol, xxx, no. 4, May 1920) ; Nonidez, " The 

 Meiotic Phenomena in the Spermatogenesis of Blaps, with Special Reference 

 to the X-complex" (Jour. Morph., vol. xxxiv, no. i, June 1920); Pixell- 

 Goodrich, " Determination of Age in Honey Bees" (Quart. Jour. Micro. Sci.. 

 vol. Ixiv., no. 2, Jan. 1920) ; and Zeleny, " A Change in the Bar Gene of 

 Drosophila melanogaster involving further Decrease in Facet Number and 

 Increase in Dominance " (Jour. Exp. ZooL, vol. xxx, no. 3, April 1920). 



Chordata. — N orris and Hughes, in " The Cranial, Occipital, 

 and Anterior Spinal Nerves of the Dogfish, Squalus acanthias " 

 [Jour. Comp. Neur., vol. xxxi, no. 5, June 1920), have provided 

 a much-needed detailed account of the anterior nerves of this 

 species. The work was done in the main upon a wax model 

 reconstruction of the heads of the species in the pup stage. 

 Useful diagrams are provided. Tracey has contributed two 

 papers on the anatomical relations of the membranous labyrinth 

 in fishes. " The Clupeoid Cranium in its Relation to the 

 Swim-bladder Diverticulum and the Membranous Labyrinth " 

 [Jour. Morph., vol. xxxii, no. 2, March 1920), and as the 

 Membranous Labyrinth and its Relation to the Proccelomic 

 Diverticulum of the Swim-bladder in Clupeoids " {Jour, 

 Comp. Neur., vol. xxxi, no. 4, April 1920). Both papers present 



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