INDIVIDUALITY OF CHROMOSOMES. I 5 



a uniform type of metaphase figure." Then in the metaphase 

 he tries to reduce all to the cross type. But I do not think his 

 drawings bear out his contention (see his drawings of Thallasema 

 Figs. 12, 13 and 14 of Plate XXXI). Especially in Fig. 13 I 

 do not see how he will get all to the cross type. 



We have the following recent papers on the Orthoptera : 

 McClung (17) indicates various shapes in his figures of the early 

 prophases and says : " But despite the multiplicity of their forms 

 these precursors of the chromosomes are all referable to a com- 

 mon type." This is a doubly split rod. Crosses in prophases 

 are the result of the gliding together of the chromatids, or parts 

 of the split rod. As a result of the concentration of the chro- 

 matin " the chromosomes in the nuclear plate appear to be simple 

 homogeneous bodies." But they have the shape of rods, crosses, 

 v's and rings. These McClung explains as the result of different 

 views of the crosses, and the gliding of the chromatids or the 

 bending of the arms of the crosses. 



The interesting fact here is that while Griffin and most of the 

 earlier writers tried to find that the chromosomes in metaphase 

 either were all the same shape or could be reduced to the same 

 type, McClung finds the various shapes in the metaphase, and 

 rings divide as rings and crosses as crosses. 



McClung (18) describes rings, crosses, figure 8, etc., in the 

 prophase in the Locustidae : "After concentration, while all 

 trace of internal structure" (chromomeres and splits) "are 

 gone, the general outline is retained and the crosses and rings 

 of the early stages are still even up to the metaphase crosses 

 and rings." 



Sinety figures a great variety in the Phasmidae, Locustidse, 

 Acrididse and Gryllidae. The different shapes in the metaphase 

 he explains by the different manner of insertion of the mantle 

 fibers. This may be "median, subterminal or terminal." But 

 this gives no reason for their shapes in the prophases. 



Schreiner (27), A. and K. E., have described very recently in 

 a hag-fish, Myxine glutinosa, and a dog-fish, Spinax nigcr, various 

 forms of chromosomes in the prophases. In Myxine the chro- 

 mosomes are concentrated into round or polygonal bodies, but 

 "in a few cases they show in this stage plainly a ring form." 



