9 
5. AGE. 
Persons from 15 to 50 3 mars of age more often contract the disease, 
as during that period they are more activeh^ engaged in outdoor work. 
The youngest case was 18 months and the eldest Tl years old. 
0. SEX. 
In 121 cases, 7G were males and 15 females, the difference being 
probably due to the greater liability to exposure of men on account 
of occupation. 
7. THE PARASITE. 
In the spring of 1902 Dr. A. F. Longewa}", secretary of the Mon- 
tana State Board of Health, engaged the seryices of Drs. L. B. Wilson 
and W. M. Chowning, of the Uniyersit}" of Minnesota, to inyestigate 
the ‘‘spotted (tick) feyer’’ then preyailing in the Bitter Root Yalley. 
These gentlemen published the results of their work in the Journal 
of the American Medical Association July 19, 1902, and in the 
report of the Montana State Board of Health for 1901-2. 
Surgeon-General lV 3 mian, of the Marine-Hospital Seryice, detailed 
Surg. J. O. Cobb to also inyestigate the disease, and his report was 
published in the Public Health Reports, yolume 17, No. 33, August 
15, 1902. 
The same }"ear Dr. F. F. IVesbrook, of the Uniyersity of Minne- 
sota, yisited Missoula and conlirnied the ffndings of Drs. Wilson and 
Chowning. His report will be found in the biennial report of the 
Minnesota State Board of Health for 1901-2. 
Wilson and Chowning noticed oyoid intracorpuscular bodies in 
stained preparations of the blood from their earlier cases. The}" did 
not determine the character or signiffcance of these bodies until they 
examined the fresh blood of case No. 91, when they found oyoid intra- 
corpuscular bodies showing amoeboid moyements. These obseryations 
they contirmed in all the later cases which they examined. To IVilson 
and Chowning, then, belongs the credit of discoyering a parasite which 
is yery the cause of spotted (tick) feyer. 
Parasites in the red-blood cells are rather common in the animal 
kingdom. The two which I desire to mention especially are those of 
malaria and of Texas cattle feyer. The parasite found in the red- 
blood corpuscles of persons suffering from spotted feyer apparently 
lies between these two. nlike most malarial parasites, it is not pig- 
mented, but, like them, it shows amoeboid moyements, thus differing 
from the Pyrosoma Ingeminum^ which is nonpigmented and without 
motion. Again, one form of the parasite found in spotted feyer is 
arranged in pairs in the red- blood cells, closely resembling the double 
form of Pyrosoma higeminum. 
