THE CHROMOSOMES IN HEREDITY. 



WALTER S. SUTTOX. 



.In a recent announcement of some results of a critical study of 

 the chromosomes in the various cell-generations of Brachystola 1 

 the author briefly called attention to a possible relation between 

 the phenomena there described and certain conclusions first 

 drawn from observations on plant hydrids by Gregor Mendel in 2 

 1865, and recently confirmed by a number of able investigators. 

 Further attention has already been called to the theoretical 

 aspects of the subject in a brief communication by Pvofessor E. 

 B. Wilson. 3 The present paper is devoted to a more detailed 

 discussion of these aspects, the speculative character of which 

 may be justified by the attempt to indicate certain lines of work 

 calculated to test the validity of the conclusions drawn. The 

 general conceptions here advanced were evolved purely from 

 cytological data, before the author had knowledge of the Mende- 

 lian principles, and are now presented as the contribution of a 

 cytologist who can make no pretensions to complete familiarity 

 with the results of experimental studies on heredity. As will 

 appear hereafter, they completely satisfy the conditions in typical 



Mendelian cases, and it seems that manv of the known devia- 



. 



tions from the Mendelian type may be explained by easily con- 

 ceivable variations from the normal chromosomic processes. 



It has long been admitted that we must look to the organiza- 

 tion of the germ-cells for the ultimate determination of hereditary 

 phenomena. Mendel fully appreciated this fact and even insti- 

 tuted special experiments to determine the nature of that organi- 

 zation. From them he drew the brilliant conclusion that, while, 



Fulton, Walter S., " On the Morphology of the Chromosome Group in Brachy- 

 stola magna," BIOL. BULL., IV., i, 1902. 



-Mendel, Gregor Johann, " Versuche iiber Pflanzen-Hybriden," Vti-fi. naturf. 

 I'ers. in ftri'tiin IV., and in Osterwald's Klassiker der e*akten Wissenschaft. Eng- 

 lish translation in Jom-n. Koy. //<;-/. Soc., XXVI., 1901. Later reprinted with 

 modifications and corrections in Bateson's " Mendel's Principles of Heredity," Cam- 

 bridge, 1902, p. 40. 



3 Wilson, E. B., ' Mendel's Principles of Heredity and the Maturation of the 

 Germ-Cells," Science, XVI., 416. 



