156 KANSAS UNIVERSITY QUARTERLY. 



ner in the equatorial plate, and in many cases the accessory chromatin 

 element cannot be distinguished from its fellows. 



7. Slightly before the occurrence of the longitudinal split of the 

 chromosomes, the centrosomes, connected by a minute centrodesmus, 

 appear in the jjortion of the cell containing the greatest mass of cyto- 

 plasm, and slowly move apart until they become diametrically oppo- 

 site each other. About this time, first the nuclear membrane, then 

 that of the accessory chromosome, is dissolved. 



8. The metaphase, anaphases and telophases occur precisely as in 

 the previous division. These processes are repeated until each cyst 

 contains secondary spermatogonia of the seventh or eighth generation, 

 when the transformation to spermatocytes occurs. 



9. In the telophases of the last spermatogonial division the saccu- 

 lations of the nucleus entirely disappear, leaving a smooth, vesicular 

 membrane, to which the vesicle of the accessory chromosome is very 

 closely applied. 



BIBLIOGRAPHY. 



1881. Balfour. Embryology. 



1885. Bioudi. Die Eotwicklung der Spermatozoiden. Ar<-hir fur iiiikro- 

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1872. von Ebner, V. Untersuchungen iiber d. Bau d. Samenkanalschen 

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1891. Henki.ng, H. Ueber Spermatogenese und deren Beziehung zur Ent- 

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1899. McClung, C. E. A Peculiar Nuclear Element in the Male Repro- 

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1898. Montgomery, T. H., jr. The Spermatogenesis of Pentatoma up to the 

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1895. Moore, J. E. S. On the Structural Changes in the Reproductive Cells 

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1899. Paulmier, F. C. The Spermatogenesis of Anasa tristis. Jonnnil of 

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1894. Toyama, K. On the Spermatogenesis of the Silkworm. Jtull. Af/rir. 

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