Vol. VIII. December, 1904. No. i 



BIOLOGICAL BULLETIN 



SOME NEW EVIDENCES FOR THE INDIVIDUALITY 

 OF THE CHROMOSOMES. 



W. J. BAUMGARTNER. 



INTRODUCTION. 



Owing to the renewed interest in hybridization aroused by the 

 rediscovery of Mendel's laws, any facts that throw light on any 

 of the theories used to explain the complex phenomena of the 

 inheritance of specific characters in crosses must be welcome to 

 biologists. In his resume of the observations on hybrids and 

 germ-cell generation Haecker (13) lays great stress on the theory 

 of the individuality of the chromosomes. The same has been 

 done by Sutton (31), Cannon (7), (8) and others. In this paper 

 I propose to publish some observations made on the germ cells 

 of crickets which furnish two lines of evidence establishing still 

 better the individuality of the chromosome. 



The first of these concerns the accessory chromosome in 

 whose behavior I have found additional proof of its distinctness 

 from the other chromosomes. 



The second line of evidence concerns the ordinary chromo- 

 somes. Boveri (5) has recently found a difference in function in 

 the chromosomes; Sutton (30) has found a difference in size; 

 and I have been fortunate enough to find a difference inform, a 

 characteristic shape assumed by the chromosomes in the pro- 

 phase and metaphase of the first spermatocyte division. 



METHODS AND MATERIAL. 



As indicated in my former paper (3), Flemming's strong 

 chromo-aceto-osmic fixative is best for the study of cricket germ- 

 cells. Thirty-five per cent, alcohol saturated with corrosive sub- 



