232 WALTER S. SUTTON. 



in the organism, maternal and paternal potentialities are present 

 in the field of each character, the genii-cells in respect to cadi 

 character are pure. Little was then known of the nature of cell- 

 division, and Mendel attempted no comparisons in that direction ; 

 but to those who in recent years have revived and extended his 

 results the probability of a relation between cell-organization and 

 cell-division has repeatedly occurred. Bateson * clearly states 

 his impression in this regard in the following words : "It is 

 impossible to be presented with the fact that in Menclelian cases 

 the cross-bred produces on an average equal numbers of gametes 

 of each kind, that is to say, a symmetrical result, without sus- 

 pecting that this fact must correspond with some symmetrical 

 figure of distribution of the gametes in the cell divisions by which 

 they are produced." 



Nearly a year ago it became apparent to the author that the 

 high degree of organization in the chromosome-group of the 

 germ-cells as shown in Brachystola could scarcely be without 

 definite significance in inheritance, for, as shown in the paper 2 

 already referred to, it had appeared that : 



1. The chromosome group of the presynaptic germ-cells is 

 made up of two equivalent chromosome-series, and that strong 

 ground exists for the conclusion that one of these is paternal 

 and the other maternal. 



2. The process of synapsis (pseudo-reduction) consists in the 

 union in pairs of the homologous members (/. t\, those that cor- 

 respond in size) of the two series. 3 



3. The first post-synaptic or maturation mitosis is equational 

 and hence results in no chromosomic differentiation. 



4. The second post-synaptic division is a reducing division, 

 resulting in the separation of the chromosomes which have con- 

 jugated in synapsis, and their relegation to different germ-cells. 



5. The chromosomes retain a morphological individuality 

 throughout the various cell-divisions. 



^ateson, W. , " Mendel's Principles of Heredity," Cambridge, 1902, p. 30. 



2 Sutton, W. S., lot: cit. 



3 The conclusion that synapsis involves a union of paternal and maternal chromo- 

 somes in pairs was first reached by Montgomery in 1901. 



Montgomery, T. H., Jr., "A Study of the Chromosomes of the Germ-Cells of 

 Metazoa," Trans. Ainet: Phil. Soc., XX. 



