THE MITOSIS OF LYMPHOCYTES 187 



As will be shown in the succeeding chapters, one 

 can now induce mitosis in lymphocytes whenever one 

 pleases, and we have seen all stages of their cell-division. 

 It must be remembered that to induce all these stages 

 occupied many months of work, and involved the em- 

 ployment of many varieties of the jelly-films. I shall 

 now describe these divisions in detail, because we have 

 since been able to induce divisions in other human 

 cells, and therefore there is reason to believe that the 

 phenomenon of mitosis in other varieties of cells is 

 similar, if not identical, with that of lymphocytes, 

 especially as regards the Altmann's granules forming 

 the chromosomes and the nuclear wall forming the 

 spindle, both of which are important cytological 

 points. 



The normal lymphocyte (figs. 40-2) occurs in a 

 great variety of sizes in the body. In the blood 

 one usually sees the smaller sizes, but in the glands 

 (and not only in the lymphatic glands) the cell may 

 reach large proportions. As will be shown later, it 

 is quite a different class of cell, cytologically, from 

 the so-called polymorphonuclear leucocyte, and it 

 must spend only a portion of its life in the peripheral 

 circulation. The lymphocyte has a large round or 

 kidney-shaped nucleus, w r ithin which there are one or 

 two nucleoli. In the living cell the nucleus appears 

 to be a transparent membrane (fig. 40) which stains 

 a faint blue with Unna's polychrome dye, 1 and it is 

 tucked in at its poles to be attached to the nucleolus. 

 Outside the nucleus, and studded on its surface, a 



1 Chromatin stains scarlet. 



