346 ON GROWTH AND OVERGROWTH 



distinguishing, I should add, between lymphadenosis (lymphatic 

 leukaemia) and myelosis (myelogenous leukaemia). For what is 

 true of the lymphoid tissue proper obtains also in respect to the 

 elements of the bone marrow ; these also may undergo diffuse 

 regional hyperplasia, with the complication that in the marrow 

 there exist elements of more than one type, and one or other of 

 these may exhibit hyperplasia. Thus in general lymphadenosis 

 the lymphocytic or lymphoblastic elements of the bone marrow 

 may be coincidently involved. In what I think we may term 

 myelosis proper (myelogenous leukaemia) it is the myelocytes 

 that in the main are hyperplastic, and this to such an extent that 

 the immature myelocytes are discharged into the blood stream, 

 and, at times, such is the stimulus to the formation of this type of 

 cell that organs like the spleen and liver resume the power they 

 possessed in embryonic life, and once again become the site of 

 myelocyte production. 



The limitations set to communications before this Congress 

 forbid that I should do more than sketch the broad outlines of 

 my subject. I can merely state that lymphadenosis (leukaemic 

 and aleukaemic lymphatic leukaemia) and myelosis (myelogenous 

 leukaemia) are system diseases, hyperblastoses of the lymphoid 

 and myeloid tissue respectively of the whole organism, which, 

 under the influence of localization and regional intensity of the 

 process in the different areas of the body, are apt to induce 

 numerous variations in the facies of the disease. Saying this 

 it is necessary, parenthetically, to exclude Hodgkin's disease from 

 this group of hyperblastoses : with the majority of recent workers, 

 I regard this as of irritative and chronic inflammatory origin, as 

 a lymphogranulomatosis. 



We must now pass on to the consideration of another feature 

 of these hyperblastoses, which for the sake of clearness I have 

 so far studiously kept in the background. I refer to their liability 

 to present malignant change. This may exhibit itself either as 

 a primary or a secondary phenomenon, and may be of localized 

 origin or generalized. It is characteristic not only of the lymph- 

 adenoses and myeloses, but of the hyperblastoses as a group, 

 that, instead of the constituent cells being of fully-formed adult 

 type, they may either locally or diffusely exhibit actively vegeta- 

 tive or " embryonic " characters. This, after all, is only what 

 might be expected from what we know of the general phenomena 



