142 THE EXCITATION OF AMCEBOID MOVEMENTS 



film must also have an index lower by one unit than 

 that for the neutrophile corpuscle. The lymphocyte, 

 or mononuclear corpuscle, also becomes excited to a 

 marked degree by absorption of atropine (figs. 31-3) ; 

 indeed they extrude longer pseudopodia than any of 

 the other classes of blood-cells, a fact which is more 

 interesting, because it is generally supposed that the 

 lymphocyte is not a very amoeboid cell, a supposition 

 which is erroneous. To induce amoeboid movements 

 in the mononuclear cells, however, it is best to treat 

 them as though they had a coefficient of diffusion 

 lower than that of the leucocytes by about one unit, 

 as these cells seem to die before the nucleus becomes 

 stained. It was pointed out in the original specifi- 

 cation that the staining of the nucleus indicated the 

 point at which the coefficient of diffusion is determined. 

 It has already been mentioned that this term nu- 

 cleus is rather vague, and, as will be shown later, 

 death is occasioned in the lymphocyte by staining 

 of the nucleolus, which frequently becomes coloured 

 before the nuclear wall. For general purposes, 

 however, the original specification stands good. 



The foregoing experiment, by which one can 

 excite amoeboid movements in leucocytes which have 

 their granules stained, proves that the staining of 

 their Altmann's granules is not very harmful to cells. 

 The granules can, and do, become deeply stained, 

 and all the while the cells will continue to extrude 

 and retract pseudopodia in response to the alkaloid. 

 This point is a very important one when we come 

 to study induced cell-division, for it affords a clue as 



