140 THE EXCITATION OF AMCEBOID MOVEMENTS 



state the formula for the index of diffusion of this 

 jelly: 



where z = the unit of atropine sulphate. 



The specimen is kept at the room temperature, or 

 3 units of heat; and the object of the jelly is to excite 

 amceboid movements in fifteen minutes (or 1 . 5 unit 

 of time) in neutrophile polynuclear leucocytes, which 

 have a cf of 12. This jelly, of course, is arranged for 

 the coefficient of diffusion of leucocytes, and it may thus 

 be set down : 



Now, if these equations are carefully considered, it 

 should be noticed that they are apparently wrong: the 

 coefficient of diffusion of neutrophile leucocytes is 12, 

 not 11. 



This brings us to another rule. It is obvious that 

 if the jelly was prepared for the exact coefficient of 

 diffusion of leucocytes, we would not obtain excitation 

 of those cells in the given time we would only obtain 

 staining of their nuclei, and staining of the nuclei means 

 that the cells would be dead. This would mean that 

 we should defeat our object, for dead cells with their 

 nuclei stained will certainly not respond to the atro- 

 pine. * The determination of the coefficient of diffusion 

 of nucleated cells involves death," because the stain- 

 ing of the nucleus is the moment by which the cf is 

 obtained. 



But this difficulty can be overcome by subtracting 



