PLATE 8 



EXPLANATION OF FIGURES 



From photographs by the author. Enlargement a little less than 1250 diameters. 

 Oncopeltus (1-5, 7-11, 16-24), Lygaeus bicrucis (6, 12-15, 25), Largus cinctus (26, 

 27). Many figures of the same preparations, from drawings, are reproduced in the 

 preceding plates, as indicated in brackets. Photos. 1-15, 26,27, from sections, 

 the others from smear-preparations. 



1, 2 Spermatogonial metaphases. Oncopeltus. 



3 First division metaphase. 



4 Second division metaphase. 



5 First division metaphase in side view, showing the sex-chromosomes in the 

 center. 



6 (Figs. 45, 46) Second division metaphases, one in polar view, one in side 

 view, showing the initial separation of X and Y. Lygaeus bicrucis. 



7-8 Stage d. Leptotene-nuclei of Oncopeltus. 



9 Pachytene-nuclei, just emerging from the synizesis. Oncopeltus. 



10 (Fig. 65). Stage/. Early diplotene-nucleus. From a smear. 



11 Stage g. Confused stage, showing plasmasome and both sex-chromosomes. 



12 Stage e. Synizesis, Lygaeus, from much extracted preparation, showing the 

 X- and F-chromosomes united. 



13 Above, the X- and F-chromosomes of Lygaeus in Stage /, attached in one 

 case end to end, in the other side by side. Below, the same from early Stage g, 

 showing also the plasmasome. 



14-15 Nuclei of Stage g, Lygaeus, showing the longitudinally divided X-chro- 

 mosome, and (at the left) the plasmasome. 



16 Nucleus of the confused period (Stage g). Oncopeltus. 



17-24 Early, middle and late prophases (Stages h-j) from smear-preparations 

 of Oncopeltus. Photo. 17 (fig. 107), 18 (fig. 108), 20 (fig. 109), 21 (fig. 111). The 

 sex-chromosomes distinguishable in each case. 



25 Late prophase-nucleus of Lygaeus (Stage i-j), the X- and F-chromosomes 

 readily distinguishable above towards the left. 



26-27 Stage b-c, in Largus cinctus. The uncoiling of spiral leptotene-threads 

 is clearly visible in the negative of photo. 27. 



446 



