" ACCESSORY CHROMOSOME IN EPEIRA. 2OI 



undivided to one pole, the eleven ordinary chromosomes dividing 

 by a reduction-division. 



4. The second maturation division is an equation division, in 

 which the old chromosome participates. 



5. Resulting from the first division are two types of secon- 

 dary spermatocytes (i) containing eleven chromosomes, plus 

 the odd chromosome, and (2) containing only eleven chromo- 

 somes. 



Resulting from the second division are two types of sperma- 

 tozoa (i) containing eleven chromosomes, plus the odd chromo- 

 some, and (2) containing only eleven chromosomes. These two 

 types of spermatozoa exist in equal numbers. 



ZOOLOGICAL LABORATORY, COLUMBIA UNIVERSITY, 

 May 1 6, 1906. 



WORKS CITED. 

 Blackman, M. W. 



'03 The Spermalogenesis of the Myriapods. Biol. Bull., Vol. V. 



Gross, J. 



'04 Die Spermatogenese von Syromastes marginatus. Zool. Jahrb., Anat. u. 

 Ontog., XX., 3. 



McClung, C. E. 



'oo The Spermatocytic Divisions of the Acrididae. Bull. Univ. Kansas, IX., I. 

 '02 The Spermatocytic Divisions of the Locustida?. Bull. Univ. Kansas, XL, 8. 



Montgomery, T. H. 



'05 The Spermatogenesis of Syrbula and Lycosa, with general considerations 

 upon Chromosome Reduction and the Heterochromosomes. Proc. Acad. 

 Nat. Sci. Phil., Feb., 1905. 



'06 The Terminology of Aberrant Chromosomes and their Behavior in Certain 

 Hemiptera. Science, XXI 1 1. 



Paulmier, F. C. 



'gg The Spermatogenesis of Anasa tristis. Jour. Morph., XV., Supplement. 



Sinety, R. de. 



'01 Recherches sur la Biologic et 1' Anatomic des Phasmes. La Cellule, T. XIX. 



Sutton, W. S. 



'oo The Spermatogonial Divisions in Brachystola magna. Bull. Univ. Kansas, 



IX., i. 

 '02 On the Morphology of the Chromosome Group in Brachystola magna. Biol. 



Bull., IV., I. 



Wallace, L. B. 



'05 The Spermatogenesis of the Spider. Biol. Bull., VIII., 3. 



Wilson, E. B. 



'05 Studies on Chromosomes, II. ^The Paired Microchromosomes, Idiochromo- 

 somes and Heterotropic Chromosomes in Hemiptera. Jour. Exp. Zool., II., 4. 



