M 'CLUNG : SPERMATOCYTE DIVISIONS OF THE LOCUSTID.K. 227 



chromosomes, the tetrads of the first spermatocytes are formed. 

 It was impossible to determine the relation of the elements of 

 the two generations, but the changes are rapid and there is no 

 intervening resting condition of the nucleus. 



3. It could not be determined whether or not the spireme 

 is continuous. A longitudinal split appears very early, and 

 shortly after the chromatin segments may be seen. These 

 soon betray at their centers an indication of the cross-division, 

 producing crosses with arms that may vary considerably in 

 relative lengths. No reason was found for considering both 

 divisions longitudinal. 



4. The typical element is granular and more or less rod- 

 shaped, with the longitudinal division merely indicated by a 

 narrow line, and with but slight elongation of the chromatids 

 along the plane of the cross-division. Various modifications of 

 this occur, by which the longitudinal cleft is much increased in 

 width at the center, the cross-arms are greatly extended, or ap- 

 proximation of the ends of the rod brought about, producing a 

 ring. * 



5. The definitive chromosomes of the metaphase are pro- 

 duced by a concentration of the prophase elements, whereby 

 they become shorter, heavier, and entirely homogeneous in 

 structure. Distinct lines of division between the chromatids 

 are not visible, but the tetrad character of the elements is 

 readily established by observing the steps in their formation. 



6. The accessory chromosome early becomes distinguishable 

 because of its peripheral position and strong tendency to stain 

 with safranin, while the remaining chromatin takes the gentian 

 violet by Flemming's three-color method. At first it appears 

 as a homogeneous plate, but later this is seen to be a closely 

 coiled thread. As the chromatin segments shorten and broaden 

 to form the chromosomes of the mitotic figure, this thread also 

 grows shorter and heavier until it forms an element of essen- 

 tially the same character as that of the spermatogonial chro- 

 mosome from which it was derived. 



7. Upon the establishment of the mitotic figure, the chromo- 

 somes arrange themselves in the equatorial plate with their 

 longer axis perpendicular to the spindle axis. Division of the 

 elements is not synchronous, so that all stages of the chromatid 

 movements may be observed in one nucleus. By this means it 



