248 Hybrids of Bistonine Moths 



Fig. 5. Early synapsis stage ; fine thread withdrawn to one side of nucleus. 



Fig. 6. Later synapsis (bouquet or pachytene stage), with coiled thick thread. 



Figs. 7, 8. Primary spermatocyte equatorial plates. 13 chromosomes, of which 



one consists of a large coupled with a small (left upper side in Fig. 7, right 



lower in Fig. 8). 

 Fig. 9, a, b, c. The compound chromosome in side view. In h the small member 



appears not to be dividing ; more commonly in metaphase all the large chromo- 



somes appear like c. 

 Fig. 10. Primary spermatocyte anaphase; two daughter groups, cut in successive 



sections. In the left group there are 13, one of which is compound ; in the right 



group there are 13 with a stained body outside the circle which is probably not a 



chromosome. 



Figs. 11—14. Secondary spermatocyte equatorial plates. In Fig. 11 there are 13, one of 

 which is clearly compound ; in Fig. 12, none is obviously compound ; in Fig. 13 the 

 small member is quite separate from the large ; Fig. 14 an abnormal figure in which 

 there are 14, one of which is compound. 



Figs. 15, 16, 17, 18. B. zonaria. 



Fig. 15. Spermatogonial equatorial plate. The chromosomes are so small and 



crowded that an exact count is impossible. There are more than 100 and less 



than 120. 

 Fig. 16. Pachytene stage of spermatocyte. The thread is thinner than in hirtaria, 



and takes a less typical " bouquet " form. 

 Fig. 17. Primary spermatocyte equatorial plate. 56 chromosomes quite clearly, of 



which four are larger than the rest. 

 Fig. 18. Secondary spermatocyte equatorial plate. 56 chromosomes, of which four 



are larger. 



Figs. 19 — 26. Hybrid, zofiaria ? x hirtaria j, (This cross yields only males.) 



Fig. 19. Spermatogonial equatorial plate. 14 large chromosomes and about 56 



small. 

 Fig. 20. Early synapsis. 



Fig. 21. Thread becoming reticular, apparently omitting the bouquet stage. 

 Figs. 22, 23. Primary spermatocyte equatorial plates. In Fig. 22, 12 or 13 large 



and 50 or 51 small ; in Fig. 23, 13 large and about 40 small ; several of the latter 



are of intermediate size, as if consisting of pairs. 

 Fig. 24. Typical chromosomes from primary spermatocyte prophases, showing 



single, equally paired, unequally paired and grouped chromosomes. 

 Fig. 25. Outline of part of primary spermatocyte spindle in side view, showing some 



chromosomes dividing, others apparently not. 

 Fig. 26, Secondary spermatocyte equatorial plate — about 9 large and 46 small. 



Figs. 27 — 32. Hybrid, hirtaria ? x zonaria i . (This cross gives females and males.) 



Fig. 27. Spermatogonial equatorial plate. About 14 large and o') small chro- 

 mosomes. 



Figs. 28, 29. Early and later synapsis stages, corresponding to Figs. 20 and 21 of 

 the converse cross. 



Figs. 30, 31. Primary spermatocyte equatorial plates. In Fig. 30 about 11 large, 

 8 or 9 intermediate, and about 40 small ; in Fig. 31, 11 large and 42 intermediate 

 and small. 



Fig. 32. Secondary spermatocyte equatorial plate. About 9 large and 41 small. 



