44 CELLULAR STAINING, DEATH, ACHROMASIA 



leucocytes to stain deeply in a given time being 

 a very definite one, as will be described in the next 

 chapter; but in the meantime we must assume that 

 a jelly has been correctly prepared containing, besides 

 the proper proportions of sodium citrate and sodium 

 chloride to keep the cells alive, the proportion of stain 

 requisite to enable us to observe its gradual passage 

 into the leucocytes as they absorb it. 



The agar jelly, of course, will be coloured purple 

 owing to the stain it holds in solution, but it will be 

 quite transparent and will allow sufficient light to 

 penetrate it so that the cells may be clearly observed. 



Having without delay placed the film, with the blood- 

 cells upon it, under the microscope, at first the cells 

 will be quite unstained, but the white corpuscles 

 may easily be recognized owing to their granulation 

 and size. Let a polymorphonuclear leucocyte be 

 watched. Gradually its granules become tinted a 

 faint red colour (fig. 6) and about the same time 

 amoeboid movements may begin. If certain propor- 

 tions of alkaloid have been added to the jelly, these 

 amoeboid movements will be very marked (fig. 7). 

 The staining of the granules becomes deeper and 

 deeper, always maintaining the same bright scarlet 

 colour. In spite of the deepening coloration of the 

 granules, amoeboid movements will continue, showing 

 that the cells are alive and that their vitality is appar- 

 ently unaffected by the staining of their granules. 

 It is not only the polynuclear leucocytes that behave 

 in this way, but the mononuclear, or lymphocyte, 

 cells as well. 



