PLATE 5 



EXPLANATION OF FIGURES 



46 Portion of tubule of 50-day rat. The tubule is cut nearly parallel with the 

 length, but to one side of the center, so that the lumen barely shows. First 

 spermatocyte prophases and metaphases are the most jironiinent cells. Simple 

 rings appear in cells just above the figure number. The darkly staining cells 

 close to the lamina propria are in the leptotene stage (toward the right) ; the cells 

 showing finely dotted nuclear contents in the same zone (to the left) are in the 

 pachytene stage. Compare figures 7 and 8. Spermatogonia are few and at the 

 stage shown in this figure are not dividing. Iron-liaemato.xj'lin. X 400. 



47 to 58 Single chromosome and complexes. Iron-haematoxylin. X 1400. 



47 shows in upper cell chromosome A in diakinesis. 



48 shows tlie character of the filaments in early diakinesis. Compare with 

 the lower cell in figure 47. 



49 Chromosome B. This photograph has been retouched to show the full 

 chromosome, as its outline follows the nuclear wall so closely that the whole 

 chromosome would not focus at one level with the oil-immersion lens. 



50 The small double ring. Compare with figure 27. 



51 A ring chromosome with widespread lugs. This chromosome is drawn 

 in figure 35. 



52 One of the large crosses in prophase. 



53 shows the accessory when the other chromosomes are in synapsis, one of 

 which appears at the left. 



54 to 56 The characteristic position and staining reaction of the accessory 

 in first spermatocyte metaphase and early anaphase. 



57 A cross in metaphase; lateral view. The neighl)oring chromosomes have 

 been obliterated in order to bring it out clearly. 



58 A polar view of the first spermatocyte complex in metaphase. This has not 

 been retouched. The same cell is drawn in figure 20. Flemming fixation. 



184 



