24 
to give some data from Idaho also. Doctor Maxey has written me 
under date of October 21, 1904. as follows: 
In view of the above findings (' and the further fact that both Doctor McCalla and 
myself had failed to obtain a history of recent tick bite in a considerable percentage 
of our cases, we were led to question the theories of- Wilson and Chowning even 
before receiving your letter. 
In considering the. possibility of infection by ticks it may be 
remarked that the tick is a verv fertile animal, laving hundreds of 
eggs, and on this account it would be expected on a priori grounds 
that if ‘‘spotted fever'’ were a tick-borne piroplasmatic disease we 
ought to find quite a number Pf cases developing in the locality where 
one case developed rather than one or two cases each in several 
widely separated localities (see p. 43). It was the limited number of 
cases in comparison with the great fertility of the tick which first 
raised my suspicions against the tick hypothesis. 
Tick bites are exceedingly common in the Bitter Root Valley; in 
fact, Dermacentor andersoni is so common that it seems rather strange 
that all of the patients did not show some history of being bitten by 
them. 
That tick bites are not alwavs of no significance is abundantlv demon- 
strated. Doctor Buckley, for instance, had a patient who was bitten 
on the arm b}^ a tick; the arm became quite swollen and the man was 
, confined to bed for some days. Doctor Parsons had a patient who 
showed an extensive lymphangitis following a tick bite. Upon several 
occasions I have seen lesions from one-fourth of an inch to 3 inches 
in diameter at the point of the tick bite. 
The Burrowing Squirrel {Citellus columbianus) as possible 
SOURCE OF Spotted Fever. 
So far as I am aware, Wilson and Chowning (1902a, p. 136) were 
the first to suggest that the burrowing squirrel or spermophile rep- 
resents the original host of this disease. Their grounds for this sug- 
gestion were as follows: 
The extreme isolation of cases of “spotted fever,” their occasional development in 
localities removed many miles from the site of any previous case, and the long 
period existing between the death or convalescence of the last case of any one year 
before the development of the fii’st case in the following year, would point to the 
possibility of the red-blood cells of some one of the lower warm-blooded animals 
being the normal host of the parasitic protozoon in that stage of its cycle not passed 
within the body of some arachnoid. Of the animals within the infected region, the 
common gray gopher would probably best fulfill the conditions of such a parasitism. 
The writers are at present attempting to obtain data which shall confirm or 
demolish the above hypotheses. 
a Namely, the inability of Maxey,. Charles E. Simon, and Cole to find any Piroplasma in blood smears 
from Idaho cases. 
