CONTAINING CENTROSOMES 53 



cells as minute pink-staining points. That they 

 are centrosomes is believed because they only 

 appear immediately before division occurs and 

 also because after they stain death of the whole 

 cell takes place and haemolysis results. In order 

 to produce this it is necessary to employ a great 

 concentration of stain combined with alkali in the 

 jelly, and to heat the specimen in the incubator at 

 blood heat for some time red blood-corpuscles 

 seem to have a vitality much more resistant to 

 these factors than leucocytes. If much stain is 

 added to the jelly the haemoglobin within the cells 

 stains, and remains stained until death and achro- 

 masia occurs, and then the stain fades as the 

 haemoglobin passes out of the cell. 



But even with this strong concentration of 

 stain with heat and alkali factors which increase 

 diffusion into cells and with the strongest 

 auxetics, divisions could not be induced in the 

 erythrocytes of healthy blood. Various concen- 

 trations of jelly were used containing varying 

 contents of stain (azur), salts, alkali, and such 

 auxetics as " globin," putrid suprarenal extract of 

 the sheep, theobromine, theophylline, creatine, 

 caffeine all substances which will induce divisions 

 in lymphocytes and leucocytes and these com- 

 bined with atropine, but without success even 

 when subjected to various degrees of heat. The 

 jellies used would frequently cause the lympho- 

 cytes to undergo their divisions, but the red 

 corpuscles remained unaffected. Even the granular 

 cells, which in cancer cases sometimes divide, re- 

 mained unmoved. 



Early last year an attempt was made to induce 

 4* 



