UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 20, No. I 1, pp. 301-307, 7 figures in text April 21, 1922 



MITOSIS IN ENDAMOEBA DYSENTERIAE IN 



THE BONE MARROW IN ARTHRITIS 



DEFORMANS 



BY 



CHARLES ATWOOD KOFOID and OLIVE SWEZY 



(Conlribution from the Zoological Laboratory, University of California, and from the Division of 

 Parasitology, Bureau of Communicable Diseases, California State Board of Health) 



The coiiieidenee of the presence of Endamoeha dysentrriae in the 

 human bowel and a diagnosis of arthritis deformans ha.s been a matter 

 of observation and record in our laboratory for several years. We 

 have previously called attention to this relation to rheumatism of the 

 joints (Kofoid, 1920). We later (1922) identified amoebae in the bone 

 marrow in material submitted by Dr. Eh^ in Ely's (1920) second 

 type of arthritis deformmis, and our discovery was announced coinei- 

 deutly by Ely, Reed, and Wyckoff (1922) with ourselves. This note 

 is a preliminary statement of the proof that the cells interpreted by 

 us as amoebae are in reality parasitic rhizopods and not amoeboid 

 human cells. 



The proof rests upon the fact that mitosis in the Rhizopoda and 

 in the Metazoa, including that in human cells, is of two distinct types, 

 clearly distinguishable by well-known cytological criterions of such 

 definiteness that there can be no pcssibility of any trained cytologist 

 or protozoologist confusing them. If the amoeboid cells found by 

 us in the bone marrow of the lesions in the excised head of the femur 

 are really amoebae, they will exhibit, when they divide, the character- 

 istic behavior and resulting morphology in fixed and stained material 

 which occurs in the rhizopods. If they are oul.y wandering amoeboid 

 human cells, they will exhibit the human type of mitosis, or, if the 

 tissue is degenerating, some modification of it. It is hardly probable 

 or po.ssible in the light of known degenerating human cells that degen- 



