LINKAGE OF CHROMOSOMES. 173 



V 



really occurs more often than my drawings would indicate. 

 Whenever the multiple is seen, whether in an entire cell or only 

 in a section, it is quite rare that the sex chromosome does not 

 accompany it. In the majority of cases, although my drawings 

 do not bear me out in this, spermatogonial figures show these 

 two elements on the same half of the periphery. The No. 560 

 material shows this particularly well. They are not connected 

 as McClung found in Mermiria ('05), and Robertson in Chort- 

 hippus ('15) but seem to be influenced or attracted by each other 

 so that they are generally found in close proximity. 



It seems to me the individuality or genetic continuity of the 

 chromosomes which Wilson ('09) speaks of, is pretty well estab- 

 lished here in at least the multiple types. In cysts that show 

 different stages of division, the V may often be distinguished 

 still intact, so that it can be traced from spermatogonia through 

 the second spermatocyte still in the V form. It is quite Hkely 

 only one half the spermatids of the one-V type receive a V while 

 each spermatid of the two-V type receive one. 



I wish to express my thanks and indebtedness to Prof. W. R. B. 

 Robertson for his helpful suggestions and encouragement during 

 the progress of this work. 



Zoological Laboratory, 



Kansas University, 

 September, 1914. 



BIBLIOGRAPHY. 

 Boveri, Th. 



'05 Zellenstudien V. Uber die Abhangigheit der Kerngrosse und Zellenzahl der 

 Seeigellarven von der Chronosomenzahl der Ausgangszellen Jen. Zeit- 

 schrift, Bd. 32. 

 Browne, E. N. 



'10 Study of the Male Germ Cells in Notonecta. Journal of Experimental 



Zoology, Vol. 14, No. i, January, 1913. 

 '10 The Relation between chromosome-number and species in Notonecta. 

 Biol. Bull., Vol. 20. 

 McClung, C. E. 



'05 The Chromosome Complex of Orthopteran Spermatocytes. Biol. Bull., 

 Vol. 9- 

 Payne, F. 



'09 Some New Types of Chromosome Distribution and Their Relation to Sex. 

 Biol. Bull., Vol. 16. 

 Robertson, W. R. B. 



'08 The Chromosome Complex of Syrbula admirabilis. Kan. Univ. Sci. Bull. 



