31 
the patients are residing or sojourning in or near the foothills of the mountains; he 
has carefully investigated this question of residence in every case coming nnder his 
observation and has found that without exception there was a history of a longer or 
shorter residence, just prior to the sickness, in or near the mountains or along some 
mountain stream where the sole water supply came from melting snow. 
Montana . — Gwinn (1902) says that in the Bitter Boot Valley at least 90 per cent of 
the cases occur on the west side of the river. Wilson and Chowning (1902a, p. 132) 
state that in ^Montana the cases are confined to the eastern foothills of the Bitter 
Root Mountains (see also above, p. 25). They describe this range as very rugged, 
the top being covered with snow until about July 1, and some peaks capped through- 
out the year; the range on the east side of the valley is less rugged, though the snow 
remains almost as long ui the spring as on the west side; on the footliills the snow 
melts from sunny exposures as early as February, the bulk of it disappearing in April 
and May; the climate of the valley is very mild, as is evidenced by the many orchards 
of apple, cherry, and plum trees; the altitude of the valley is about 3,500 feet above 
sea level. In their later papers (1903a, pp. 42, 67; 1904a, pp. 33, 34, 43) they prac- 
tically repeat these statements, laying stress upon the locahzation of the Bitter Root 
Valley infection to the foothills on the west side. They do not discnss the topog- 
raphy of the Rock Creek cases. 
Anderson (1903a, p. 506; 1903c, p. 8), in discu-ssing the localization in the Bitter 
Root Valley, says that the disease is sharply localized on the west bank of the 
Bitter Root River, no case ha^'ing been known on the east side of the river who had 
not a short time previously \dsited the west side. Certain places, he states, seem to 
be more heavily infected than others. 
From the list of cases for 190T. given on page 26. it will be .seen that 
these statements as to localization are borne out to a certain extent, 
but that while 6 cases occurred on the west side of the Bitter Root 
River, 1 case certainly occurred on the east side, and in 4: other cases 
no emdence was obtained that the patients had visited the west side 
shortly before their illness (except that one had passed through on a 
train). 
In connection with the larger' number of cases on the west side it 
should be mentioned that there is a marked difference in general con- 
ditions between the east and west sides. On the west side there is 
much more timber and underbrush: the west .side is narrower than 
the east and is watered by more numerous mountain .streams, as is 
.shown in the map published by Wilson and Chowning (1903a) and 
Anderson (1903c). In driving through the valley one is struck by the 
difference in the general conditions of moisture (the ea.st side being 
less damp) and by the generally better economic and hygienic condi- 
tions than on the we.st side. 
In this connection, however, it is interesting to note that there is a 
short stretch of land, several miles in length, on the west side, between 
Carlton and Lo Lo. for which neither Wilson and Chownmg (1903a. 
map) nor Andersen (1903c, map) report any cases of .spotted fever for 
the years 1885 to 1903, inclusive. This particular locality resembles, 
in condition, the east .side much more closely than does any other 
portion of the we.st side between Lo Lo and Hamilton. Remarking 
upon this point to one of the farmers in the locality in cpiestion. I was 
