2634 Journal of Applied Microscopy 



NORMAL AND PATHOLOGICAL HISTOLOGY. 



JOSEPH H. PRATT, Harvard University Medical School. 



Books for Review and Separates of Papers on these Subjects should be Sent to Joseph H. Pratt, 

 Harvard University Medical School, Boston, Mass. 



^ . , , . A careful histological study by Reed 



Reed, Dorothy. A case of acute lymphatic 



leukjemia without enlargement of the lymph supports the view of Walz and Pappen- 

 glands. Am. Jour. Med. Sci. 1902, cxxiv, j^gj^j^ ^1^^^ [^ ^^^^.y ^ase of leukaemia 

 p. 653. . . . 



the primary seat of the disease is in 



the bone marrow. The old theory that lymphatic leukemia is essentially a dis- 

 ease of the lymph nodes, is still supported by Ehrlich. He bases his claim on 

 the assertion that no lymphocytes occur normally in the bone marrow. This 

 statement the writer calls into question, as in the bone marrow cells are found 

 identical morphologically with the lymphocyte. There is no proof that the 

 lymphocytes of the blood come from the lymph glands alone, and although it 

 cannot be stated positively that they arise in the bone marrow it is known that all 

 other colorless cells of the adult blood originate in the bone marrow from lymphoid 

 cells and that cells identical morphologically with the lymphocytes of the blood 

 are found there. 



The case upon which this study was based ran a rapid course. Haemor- 

 rhages, anaemia and progressive weakness were the chief clinical features. A 

 thorough study of the blood was not made during life. At autopsy neither spleen 

 nor lymph nodes were enlarged. The bone marrow of the femur was homogene- 

 ous, deep red, and very soft. Microscopically the bone marrow consisted chiefly 

 of lymphoid elements. The predominating cell was smaller than the red blood 

 corpuscle and possessed a densely staining homogeneous round nucleus, and a 

 small amount of clear protoplasm. There was another type of lymphoid cell 

 varying in size which possessed a nucleus relatively large in respect to its proto- 

 plasm. The nucleus always showed a definite chromatin network. The cell was 

 identical in structure with the lymphocytes of the blood and of the lymph nodes. 

 There was no indicatiou of hyperplasia in either the spleen or lymph nodes. 



This case is not unique. Six similar cases have been recorded within the 

 last few years, and authorities are now nearly agreed that in lymphatic leukaemia 

 the blood changes do not occur until the bone marrow is involved. No case of 

 leukaemia has come to autopsy in which the bone marrow was normal. 



If leukaemia is always a disease of the bone marrow it is manifestly incorrect 

 to restrict the term Myelogenous to one form of the disease. The writer sug- 

 gests a new clinical classification based upon the blood picture. Three forms 

 of leukaemia are recognized, all due to myelogenous changes, — the myelocytic, 

 the lymphoid, and the mixed cell varieties. Leukaemia resembles an infectious 

 disease. Possibly in leukaemia a positive chemiotaxis exerted by some poison in 

 the body draws out certain cells from the bone marrow into the blood. 



J. H. P. 



