CHROMOSOME COMPLEX OF SPERMATOCYTES. 33! 



environments, now one character would appear, now the other, 

 and so produce the piebald result. Again we might conceive 

 that the difference between two alternatives was so considerable 

 and the disturbance of normal conditions so violent that the whole 

 organization of the chromosomes would be upset with the result 

 that a character distinct from that of either parent would be pro- 

 duced. These various alternatives are realized experimentally 

 and I can see no simpler or more consistant explanation for them 

 than the one I have presented. 



3. Multiple Chromosomes and the Chromosome Complex. 



As I have indicated already, there occur in Hesperotettix and 

 Mcnniria peculiar associations of chromosomes that are consistent 

 from generation to generation of organisms. This can be no 

 accident and undoubtedly has some fundamental meaning. It 

 seems evident that the characters owe their orderly sequence in 

 development to the organization of the germ cell elements and 

 not alone to the mere presence of a particular chromosome. 

 The experimental work of Boveri upon echinoderms and Ascaris 

 would indicate the high importance of the individual chromosome, 

 while the observations of Conklin upon the ascidian egg argues 

 strongly for the view that what the chromosomes are able to 



o 



accomplish in development depends largely upon the materials 

 on which they have to operate although we must not forget 

 that these materials are ' probably produced by the action of 

 chromosomes that came from the same original cell as do those 

 of the germ cells. 



It seems to me that these apparently somewhat contradictory 

 observations speak unmistakably for the idea of precise organi- 

 zation in the germ cells and for mutual interaction between their 

 parts. This thought comes home to me with particular emphasis 

 after a study of the unusual precision in the arrangement of the 

 cell parts of the spermatocytes of Mcnniria. The evidence of 

 the pentivalent multiple chromosome is of special importance for 

 it shows that in order to maintain the identity of the chromatin 

 complex from generation to generation there must be an accuracy 

 not only in the division of the chromosomes in maturation but 

 also in their coming together in fertilization. If it were not for 



