252 THE DIVISION OF LEUCOCYTES 



a chemical agent, and since the quantity of the agent 

 required must increase with the rapidity at which we 

 wish mitosis to occur, it is obvious that a greater con- 

 centration of the chemical agent will be required to 

 induce a division in the "experimental ten minutes" 

 than would be required to make a cell reproduce itself 

 if it were resting in its normal surroundings, where it 

 might take a much longer time in its division. 



The second corollary is that if the jelly on which 

 the cells are resting contains a saturated solution of a 

 given substance which is diffusing into the cells to the 

 utmost in ten minutes, and if that substance does not 

 induce divisions in the "experimental ten minutes," it 

 does not prove that that substance will not within the 

 body, with the cells in their natural surroundings, cause 

 them to proliferate. 



It was a matter of concern to us that the azur 

 dye did not make the polymorphonuclear leucocytes 

 (fig. 76) divide. So far only lymphocytes responded. 

 If the contention was correct that the dye contains a 

 specific agent which was possibly analogous to some 

 similar agent in the body which causes proliferation 

 of lymphocytes, it appeared reasonable to expect that 

 some similar agent, if not an identical one, would also 

 cause divisions in leucocytes; for the latter cells always 

 proliferate together with, and to a greater extent than, 

 lymphocytes during the process of healing. So far, 

 however, we had not seen anything resembling a 

 division in a polymorphonuclear leucocyte. It must 

 be admitted that we had no idea as to what a leuco- 



