92 "COEFFICIENT OF DIFFUSION OF CELLS" 



a fresh film is made from the same jelly, and it is kept 

 at a higher temperature or so many more units of 

 heat and again examined. If again it is found that the 

 nuclei are not stained at the end of, ,say, half an hour, 

 a fresh jelly is made, but with more units of alkali or 

 stain, or both, added to a fresh Solution 2, which is 

 added to a fresh tube of "coefficient jelly." If the 

 nuclei still again remain unstained, one must try more 

 units of time and more units of heat again. Thus we 

 can go on trying fresh jellies, each of which contains 

 more units of alkali, or of stain; and we try each jelly 

 for a few minutes, first at a low temperature and then 

 with a few more units of heat, until at last we find that 

 the nuclei of the cells are just beginning to stain. The 

 number of units of stain, alkali, heat, time, etc., of each 

 film is noted on a piece of paper, and therefore there is 

 no difficulty in knowing exactly how many units the 

 jelly contained which was instrumental in staining the 

 nuclei of the cells. The units of this jelly are then 

 written out in the form of an equation, and those 

 which retard diffusion i.e. the units of the salts- 

 are subtracted from those which increase diffusion, 

 the difference being the number which is the co- 

 efficient of diffusion of the class of cells experimented 

 with. 



Examples. We wish to find the cf of the neut.ro- 

 phile polynuclear leucocyte. A small quantity of 

 citrate solution is drawn up into a capillary tube, as 

 already described, and, the finger having been pricked 

 and a small bead of blood squeezed out, an equal 

 volume of blood is added to the citrate solution in 



