12 W. J. BAUMGARTNER. 



assimilis, I very much question the correctness of Sinety's inter- 

 pretation of similar appearances in Lcptynia. But my own results 

 show too great differences in detail between species of one genus 

 for me to deny the results of another worker on a different family 

 without seeing the form he studied. 1 



I can add the following new facts concerning the behavior of 

 the accessory chromosome. In the first spermatocyte spindle I 

 have a greater variation in the position in which the accessory 

 may be found. Beside the positions described by the above 

 writers it may be in the equatorial plate region and as I believe 

 constricted by the cleavage of the cell. That it is not a normal 

 division of the accessory chromosome is proven by the fact that 

 the parts separated may be unequal. It is simply a mechanical 

 separation of the chromatin mass. 



The behavior of the accessory chromosome in the semiresting 

 stage is parallel to conditions which Sutton (29) has described in 

 the spermatogonia of Brachystola. Sutton finds that the accessory 

 always has its own vesicular wall and does not form a part of the 

 regular nucleus. In Gryllus the accessory has its own vesicle in 

 the semiresting stage between the first and second spermatocytes. 

 The accessory here shows its independence in the part of the 

 germcycle in which it has not been described, and so it offers 

 additional proof of its own individuality, hence of the individuality 

 of the chromosomes. 



In the variety of shapes found in the first spermatocytes I do 

 not claim to have anything new. But in interpreting the different 

 forms as distinctive of individual chromosomes, I have assumed 

 a new view point. Anyone following the investigations on germ- 

 cells since Weismann (33) postulated a reduction division and 

 Flemming (10) distinguished between heterotypic and homotypic 

 mitoses will find a great number of shapes of chromosomes 

 described. Some of these are characteristic of certain species. 

 Other species have a great variety of shapes in the same cell. 

 The efforts of the workers who have found these different shapes 



1 Dr. McClung informs me privately, since the above was written, that he ha? 

 found appearances in an Acridids which indicate that the accessory chromosome may 

 unite with an ordinary chromosome forming an L-shaped mass; and so Sinety's in- 

 terpretation is probably correct. But the accessory is not a part of the L-shaped 

 chromosome in G. assimilis. 



