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 m- 

 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 inetaphase-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 



