REDUCTION DIVISIONS 239 



In experimenting with this last jelly containing 

 azur dye, an important point was found out. By 

 delaying death as long as possible, by employing the 

 minimum amount of alkali w r hich will make the cells 

 undergo mitosis, we at last succeeded in keeping the 

 lymphocytes alive for twenty minutes, and yet mitosis 

 was being induced during the greater part of the time. 

 That is to say, mitosis was induced as early as pos- 

 sible, for, as will be shown in the next chapter, we 

 cannot, under the experimental conditions, keep up 

 the cell's vitality longer than twenty minutes, and it 

 is difficult to keep them alive to divide for a longer 

 time than even ten minutes; still their lives have been 

 prolonged for tw r enty minutes. 



The point revealed by this experiment was that 

 the so-called reduction division is not a special form 

 of mitosis in lymphocytes. The somatic number of 

 chromosomes in the body is thirty-two, but hitherto 

 in all the dividing lymphocytes in which it was pos- 

 sible to count the actual number of chromosomes their 

 number was either sixteen or thereabouts (figs. 62, 63, 

 67). In other words, the divisions which we induced 

 with the stain in ten minutes were of the reduced 

 variety, or what Farmer, Moore, and Walker called 

 "maiotic" divisions. By prolonging life, however, for 

 twenty minutes, and inducing the divisions slowly, 

 especially if only the early stages of mitosis were 

 induced in the time, it was found that now lympho- 

 cytes divided by somatic divisions with more than 

 sixteen and sometimes with a full number of thirty- 

 two chromosomes (figs. 74, 75), and the statement 



