1 82 L. B. WALLACE. 



earnestly tried to demonstrate it but so far the method of locomo- 

 tion of the spider spermatozoon remains an unsolved mystery to 

 me. In a future paper I hope to be able to give some light upon 

 this subject as well as upon the role played by the accessory 

 chromosomes in fertilization. As my work now leaves it, the 

 functional spermatozoa would contain an uneven number of 

 chromosomes - - nineteen ordinary ones and two accessory 

 chromosomes, and it is not clear how the somatic number of 

 forty chromosomes is made up in the cleavage nucleus of the 

 ovum unless it be found that accessory chromosomes are thrown 

 off in the polar bodies, thus leaving the mature ovum with only 

 nineteen chromosomes. These nineteen, added to the twenty- 

 one brought in by the spermatozoon would make the total 

 required ; forty chromosomes. 



SUMMARY. 



1. The spermatogonia contain two accessory chromosomes 

 and thirty-eight other chromosomes. 



2. In the primary spermatocytic division the two accessory 

 chromosomes pass over undivided into one of the daughter cells. 

 The reduced number of other chromosomes is nineteen and these 

 divide transversely. 



3. In the secondary spermatocytic division, the two accessory 

 chromosomes again pass over undivided into one of the daughter 

 cells. The nineteen other chromosomes divide longitudinally. 



4. Only one fourth of the spermatozoa contain the accessory 

 chromosomes. 



5. Apparently the remaining three fourths of the spermatozoa 

 degenerate after almost or altogether reaching maturity. In this 

 respect they are regarded as homologous to the polar bodies 

 thrown off by the ovum. 



THE UNIVERSITY OF PENNSYLVANIA, 

 June, 1904. 



BIBLIOGRAPHY. 

 Baumgartner. 



1902 Spermatic! Transformations. Kans. Univ. Sci. Bull., Vol. I. 

 Blackman, M. W. 



1903 The Spermatogenesis of the Myriapods. Biol. Bull., Vol. V. 



