352 H. HONDA. 



mosomes. In the first maturation division five of the ten chromo- 

 somes are larger and five of them are smaller, but in this case six 

 are larger and four are smaller. The reason for this is discussed 

 later on. As in the case of the first division, chromosomes are 

 connected by linin threads. When the split chromosomes shift 

 to the opposite poles interzonal fibers appear. In the first divi- 

 sion the middle part of the two daughter cells becomes narrow 

 and show's an appearance of a dumb-bell with the ends different 

 in size. In this case, however, the middle part is broad, so that 

 the interzonal fibers are separated (Fig. 15). 



3. Smaller Secondary Spermatocyte. 



The smaller secondary spermatocyte shows chromosomes in its 

 nuclear cavity at the telophase of the first maturation division. 

 It is not difficult to distinguish the smaller secondary spermato- 

 cyte as their diameter is hardly half that of the larger ones. The 

 nucleus does not enter a resting stage. I have found in some 

 cases two small bodies near the nuclear membrane (Fig. 9). 

 These seem to be centrosomes, but I am unable to speak with cer- 

 tainty. The changes in preparation for the second division are 

 similar to those of the larger spermatocyte. 



The equatorial plate (Figs. 20 and 21) shows eight chromo- 

 somes as compared with ten chromosomes in the equatorial plate 

 of the larger secondary spermatocyte. The cases which distinctly 

 show eight chromosomes are rare ; there can be little doubt, how- 

 ever, that this is the full number since there are ten chromosomes 

 in the equatorial plate of the first maturation division, and two 

 of them pass to the larger one as the lagging chromosomes. Four 

 chromosomes are larger and the other four are smaller. There 

 are five larger and five smaller chromosomes in the equatorial 

 plate of the first division ; the lagging chromosomes, therefore, 

 must be a larger and a smaller chromosome. If all the chromo- 

 somes were to divide in the first division, five larger and five 

 smaller chromosomes would appear in the equatorial plate of the 

 second division. Two chromosomes, one larger and one smaller, 

 lag and enter the larger cell without dividing. The smaller of 

 the lagging chromosomes, consequently, becomes larger than the 



