PLATE 7 



EXPLANATION OF FIGURES 



From smear-preparations of Protenor; 2250 diameters; (lettering as in the pre- 

 ceding plate). 



121-127 Middle prophases (Stage i) showing all the chromosomes. The 7?^- 

 chromosomes, now condensed, are separate in all but 124. In 126 the large biva- 

 lent is a straight rod; in 127 it is such a rod bent at the middle point to form a V 

 (here seen edgewise so as not to show the longitudinal cleft. Some of the same 

 nuclei are shown in photos. 41, 44, 47. 



128 (photo. 43) Abnormal nucleus in which the large bivalent is represented 

 by a pair of separate univalents (B, B) that have failed to unite in synapsis. 



129-131 Late prophases (Stage j). In 131 the chromosomes are ready to enter 

 the metaphase-plate; (fig. 131 also in photo. 51). 



132-134 Early metaphases. In 132 one of the small bivalents and the m-chro- 

 mosomes appear abnormally large, owing to flattening. In 134 the ring tetrad 

 to the left has been slightly displaced in order to show it more clearly. 



444 



