30 



THEOPHILUS S. PAINTER 



The question now arises, what is the explanation for the 

 bipartite body which Jordan figures, as going undivided to one 

 pole of the first maturation spindle, and which he interpreted as 

 being the X-chromosome? The probable answer is, that what 



Text fig. 7 Side views of the first maturation spindle, showing displaced 

 tetrads which would appear as true sex-chromosomes in poorly fixed material. 

 The X-Y chromosomes are visible in two of the spindles. 



Jordan saw was either a displaced tetrad or half of a tetrad, the 

 other half remaining in the equatorial plane of the spindle. Such 

 conditions are not rare in my material. In text figure 7, several 

 cells are figured, in which a tetrad has been displaced and appears 



