278 THE PATHOGENIC HEMOSPOR1DIA 



tion, occurring during the spring and early summer in the high valleys 

 in the mountains of Montana and Idaho. The disease is conveyed 



V 



to man by the bite of ticks (Dermacentor reticulatus occidentalis), and 

 may be transmitted by them to rabbits, guinea-pigs, and monkeys as 

 well (King, 1906; Ricketts, 1906), while the experimental animals 

 show a high degree of immunity after one attack of the disease. 



Unfortunately, authorities do not agree as to the cause of the disease. 

 The transmission and general course of the disease, enlargement of 

 the spleen, immunity, etc., are not against the facts of piroplasmosis, 

 and this was the view taken by Wilson and Chowning ('02), who dis- 

 covered minute bodies in the erythrocytes of infected blood, both 

 fresh and stained. They named the organism Pyroplasma (Piro- 

 plasma) Babesia hominis, and were the first to suggest that ticks were 

 the agents of transmission, while the gopher (Spermophilus colum- 

 bianus) was regarded as the natural host or reservoir of the parasite. 

 Anderson ('03) confirmed the observations of Wilson and Chowning, 

 and noted with them the characteristic ameboid movements of the 

 parasites within the erythrocytes, and the frequent occurrence of twins 

 so characteristic of babesia. Their observations, descriptions, and 

 figures were not convincing, however, and others, notably Stiles ('05), 

 Ricketts ('06), and King ('06), failed completely to find the bodies 

 either in fresh or postmortem blood. Boggs ('07) states that some of 

 Wilson's and Chowning's descriptions and figures resemble blood 

 platelets, while others appear like the "navicular body of Arnold," 

 and like endothelial degenerations of various kinds. 



None of Wilson and Chowning's critics have been able to demon- 

 strate any other disease-causing organism, either by bacteriological, 

 pathological, or cytological methods, and their negations or compari- 

 sons with previously known bodies, or with structures from that 

 unlimited field of ill-defined possibilities, degeneration forms, cannot 

 offset Wilson and Chowning's positive findings and the collateral 

 evidence, and their "organism" must receive the benefit of the doubt 

 until more definite observations on the cause of Rocky Mountain 

 spotted fever are made. It is certainly interesting, in this connection, 

 that Gotschlich ('03) and other investigators have noted the presence 

 of protozoa in the blood of victims of Egyptian typhus fever, the 

 former describing an " apiosoma " (babesia) in the erythrocytes. 



Darling ('08) has recently described similar structures, under the 

 name Histoplasma capsulatum, in the blood of natives of tropical 

 America, and in endothelial cells lining blood and lymph vessels, 

 spleen, liver, lungs, and bone-marrow. The symptoms are spleno- 

 megaly, emaciation, and irregular remittent temperature. The organ- 

 isms are characterized by irregular masses of chromatin and an occa- 

 sional small deeply staining dot which may be a blepharoplast. If 

 the author's surmise is correct, that the organism has a flagellated 



