SEX-CHROMOSOMES OF PSYCHID.E. 



401 



of the daughter-plates, the homologous pairs can be identified 

 with considerable certainty. In Figs. 13 and 14, again showing 

 two sister-plates, the X-chromosome lies centrally. 



Table I., which follows, gives a summary of selected cases in 

 which both daughter-plates lie entirely in the same section, and 

 which in other respects fulfill all the conditions of demonstrative 

 clearness. Table II. summarizes the number of observed cases 

 in which the X-chromosome as seen in lateral views of the spindle, 

 is passing towards the outer or the inner pole. The result 

 permits us to predict the primary sex-ratio to be expected in 

 Taltxporia. Those X-chromosomes that pass outwards enter 

 the polar body, those that pass inwards divide equally in the 

 second maturation-division and enter the female pro-nucleus. 



TABLE I. 



