M 'CLUNG : SPERMATOCYTE DIVISIONS OV THE LOCUSTID.E. 229 



10. From each first spermatocyte there are formed, by two 

 divisions, four spermatids, of which two are distinguished from 

 the remaining pair by the possession of an extra chromosome 

 in addition to the number — sixteen — common to them all. 

 Both classes undergo a like series of transformations by which 

 they become mature spermatozoa. These are necessarily of 

 two kinds ; and it is believed that those containing the acces- 

 sory chromosome, in the act of fertilizing the egg, determine 

 that the germ-cells of the embryo shall be sexually male, or like 

 themselves, while those from which it is absent are unable to 

 impress their sex upon the egg and assist in producing female 

 embryos. 



VII. BIBLIOGRAPHY. 



1. Atkinson, Geo. F., 1899. Studies on Reduction in Plants, 

 Bot. Gaz., vol. 28. 



2. Baumgartner, W. J., 1902. The Spermatid Transforma- 

 tions of Gryllus assimilis, etc., Kans. Univ. Sci. Bull., vol. 1, 

 No. 1. 



3. Brauer, A., 1893. Zur Kenntniss der Spermatogenese von 

 Ascaris megalocephala, Arch. mikr. Anat., vol 42. 



4. Carnoy, 1895. La Cytodierese chez les Arthropodes, La 

 Cellule, vol. 1. 



5. Cholodkovsky, N., 1894. Zur Frage fiber die Anfangs- 

 stadien der Spermatogenese beiden Insecten, Zool. Anz., vol. 17. 



6. Griffin, B. B., 1899. Studies on Maturation, Fertiliza- 

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7. Hacker, Valetin, 1897. Ueber weitere Uebereinstim- 

 mungen zwischen den Fortpflanzungsvorgangen der Tiere und 

 Pfianzen, Biol. Cent., vol. 17. 



8. Henking, H., 1890. Untersuchungen iiber die ersten 

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 Spermatogenese und deren Beziehung zur Eientwicklung bei 

 ri/rrliocoris aj)terus M., Z. wiss. Zool., vol. 51. 



9. Henking, H., 1892, idem. 3. Specielles und Allgemeines, 

 ibid., vol. 54. 



10. Ischikawa, 1891. Studies of Reproductive Elements. 

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11. Kingsbury, B. F., 1902. The Spermatogenesis of Des- 

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