84 APPLIED PHYSIOLOGY 



The mother cells of the granular leucocytes in the 

 marrow are large clear cells with a single nucleus 

 (' lymphoid ' cells). By the deposition of granules in 

 their protoplasm these become converted into granular 

 myelocytes in which the nucleus is still single, and 

 these are the cells so largely present in the blood 

 in myelogenous leukaemia. The nucleus subsequently 

 becomes contorted or apparently subdivided when the 

 cell takes rank as a polynuclear leucocyte. It is believed 

 by some that the so-called * large lymphocytes ' met with 

 in the blood in the acuter forms of lymphatic leukaemia 

 are identical with the original * lymphoid ' cells. Some 

 (e.g., Wolff) go so far as to regard the lymphoid cell as 

 the original parent from which all the cells of the blood 

 are derived, according to the following scheme : 

 Lymphoid cell. 



Large lymphocyte. Erythrocytes. Myelocytes 



Small lymphocyte. (a) Basophil. 



(&) Neutrophil. 



Polynuclear leucocytes 



(a) With basophil granulation. 

 (/3) With neutrophil granulation. 



In process of development, according to ihis view, 

 a gradual differentiation of function takes place on the 

 part of the blood-forming organs, in consequence of 

 which the lymphoid cells of the marrow confine them- 

 selves to the production of granular cells, whilst those 

 of the adenoid tissue become exclusively concerned in 

 the production of non- granular cells (lymphocytes). 

 The specialization, however, is never so complete but 



