26 



Two othcF cells may with advantage be described here. 

 They occur in the blood under abnormal conditions, and are 

 of great importance in the normal development of the finely 

 and coarsely granular eosinophil cells. 



I refer to the myelocyte or marrow cell of which there are 

 two important varieties : 



1. A large mononuclear cell with fine oxyphil 

 granules — the nucleus frequently centrally placed. 



There is little or no amoeboed movement on the 

 warm stage. 



2. A similar cell in which the granules are large 

 and coarse. 



At this point 1 think it would be well to emphasize that 

 there are two large groups of leucocytes in the normal blood. 



First. Mononuclear lymphocytes, large and small, 

 free from granules, they have not the power of 

 contraction. 



Second. Polymorphonuclear cells with either fine or 

 coarse eosinophil granules. 



The origin of these two groups is entirely different, and a 

 few words may with advantage be said on this subject before 

 proceeding to the matter of the paper. 



Many different views are held as to the genesis of the 

 leucocytes. I shall not attempt to discuss them, but 

 briefly state one, that held by Ehrlich, the great master in 

 hicmatology. 



He holds that the lymphocytes of the blood originate in 

 the lymphatic system. Any increase in their number is 

 probably due to the local stimulation of certain glandular 

 areas. 



Lymphocytosis — that is an increase of the lymphocytes 

 in the blood — is due to a raised lymph circulation occurring in a 

 more or less extended area of lymphatic glands. It must be 

 regarded, therefore, as the result of a mechanical process. 



