CHROMOSOME COMPLEX OF SPERMATOCYTES. 329 



Button's views are formulated from careful comparison of size 

 relations of chromosomes in the different generations of the male 

 germ cells of Brachystola and represent the detailed proof of the 

 conception expressed in more general terms by Montgomery. 



Regarding the main view that the reduced number of chro- 

 mosomes in the maturing germ cells is brought about by definite 

 fusion of simple chromosomes into multiple ones of bivalent 

 value, there now appears to be a pretty general agreement, and 

 the older conception of a variety of processes has given way to 

 the conviction that the same plan may be detected in all organ- 

 isms when sufficiently studied. The final step in this direction 

 is to regard this fusion of elements as a definite one between the 

 same members in different generations of organisms. Such a 

 correlation between germ cell architecture and somatic structure 

 would be purely theoretical were it not for the fact that in the 

 operation of Mendel's law there is an exact parallel between what 

 is accomplished for the chromosomes in the maturation divisions 

 and for particular characters in hybrid matings. While this is 

 not an exact proof it raises the probability almost to a certainty 

 and makes it practically impossible to doubt the accuracy of the 

 hypothesis so far as it applies to purely Mendelian characters. 



It is known, however, that many characters do not follow the 

 course of those denominated Mendelian, and it now appears from 

 the observations recorded in this paper that the simplicity of 

 behavior by the chromosomes, assumed always to occur at the 

 time of germ cell maturation, is not universal. The question 

 naturally arises, then, whether the extremely simple explanation 

 offered by Sutton is sufficiently inclusive. 



Attention has already been called in previous papers to the 

 probable importance of the prophase of the first spermatocyte 

 in the matter of the hereditary transmission of characters. Upon 

 the theory of the union of homologous chromosomes into pairs 

 by synapsis * the nature of this becomes evident, for in the grass- 



1 By synapsis I mean the fusion of simple chromosomes into multiple ones, usually 

 of bivalent value, according to the idea of Moore, who proposed the term. I would sug- 

 gest that in order to avoid the lamentable confusion that has resulted from the misuse 

 of this designation that a new descriptive word be applied to the condition of the nu- 

 cleus in which the chromatin is found massed at one side of the vesicle, without 

 regard to whether it is a normal phenomenon or not. To carry out this idea I shall 

 call this stage the " synizesis" of the chromatin. 



