306 University of (Jalifoniia Publications in Zoology [Vol. 2f) 



The presence of the amoebae in the lesions of Ely's second or non- 

 bacterial type of arthriti.^ deformans supplies the missing etiological 

 factor in this disease. The term, amoebiasis of the bones, would 

 therefore more accurately link the disease with its causative organism, 

 in the event that an etiological relationship is confirmed by future 

 work. 



The question as to the exact species of amoeba found in the bone 

 lesions is perhaps still an open one. It can not be Council mania 

 lafleuri, which has eight chromosomes and a granular karyosome. The 

 only amoebae definitely known to be tissue invaders are Endamocba 

 dysenteriae and E. gingivnlis. Mitosis and chromosome number in 

 the latter are unknown. In our material and in published accounts 

 of this species, the morphologj' of the micleus difl:'ers in one minor 

 particular, the absence of spoke-like radiations. In view of this fact, 

 we tentatively incline to the view that the amoeba in the bone lesions 

 is E. dysenteriae rather than E. gingivalis, on the assumption and 

 perhaps rather widelj- accepted view that the two are distinct species. 

 There is no satisfactory evidence that they are identical, though evi- 

 dently rather more closely related in morphology to each other than 

 is either to any of the other amoebae of man. 



SUMMARY 



Active amoeboid cells with the type of nucleus found in the cysts 

 and active stages of Endmnoeba. dysenteriae in the bowel and in 

 active amoebae in the lesions of amoebiasis are found in the lesions 

 of the bones in arthritis deformam of Ely's second or non-bacterial 

 type. These amoebae at mitosis have an intact persistent nuclear 

 membrane, a meridional intradesmose, and a small number of chromo- 

 somes, probably six. This type of mitosis is that of the Rhizopoda, 

 not of the Metazoa, Mammalia or man. It is in these details exactly 

 similar to that found in E. dyscnteriue of the bowel. Human cells at 

 somatic mitosis have, excluding sex dilferences, 24 (diploid) or 48 

 (tetraploid?) chromosomes, no intradesmose, and the nuclear mem- 

 brane disappears. The mitoses in the amoebae appear to be normal, 

 and no intergrades with degenerating human cells have been found. 

 The amoeba of the bone lesions appears to be E. dysenteriae rather 

 than E. gingivalis of the gingival abscesses and tonsils. The morpho- 

 logical evidence supports the conclusion that E. dysenteriae is the 



