POSSIBILITY OF INCREASED AREA OF FEVER. 11 
the Rocky Mountain region, a very large amount of information 
was obtained. In fact the correspondents sent in altogether 1,400 
lots of ticks, 850 of which were of the fever species. These repre- 
sented 225 localities in California, Colorado, Idaho, Montana, 
Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. 
Very many of the ticks received during the course of this work 
were in immature stages. Unfortunately our present knowledge of 
ticks is not sufficient to enable us to determine the species to which 
immature forms belong. This necessitates very special care in rear- 
ing to maturity the immature forms received. This work was done 
at Dallas, Tex., and naturally involved a large amount of skilled 
attention. 
The information now in hand regarding the spotted-fever tick was 
greatly increased through the cooperation of the Biological Survey 
of this department. In 1910 two agents of this survey, Messrs. A. H. 
Howell and C. Birdsej^e, were located at the camp laboratory of the 
Bureau of Entomology near Florence, Mont. These agents were 
engaged in the collection of wild mammals upon which one stage or 
another of the spotted-fever tick occurs. This work resulted in 
showing the relative importance of the different mammals found in 
the Bitter Root Valley and adjacent mountains as carriers of the 
spotted-fever tick. It also revealed many points having a bearing 
on the original source of the disease in nature and on other impor- 
tant matters. The Biological Survey has also studied carefully the 
possibility of the eradication or control of all the wild mammals 
which carry the fever ticks. 
In September, 1910, Prof. IT. A. Morgan, director of the Tenm ss 
Experiment Station, consented to make a trip to the Bitter Root 
Valley and to advise the forces cooperating regarding the sufficiency 
of the data obtained and the feasibility of plans of eradication based 
thereon. 
Of course the authors have made full use of the available literature 
on the investigations that have been conducted by other persona 
Most useful have they found the first and second spotted-fever re- 
ports of Dr. H. T. Ricketts, published in the Fourth Biennial Report 
of the State Board of Health of Montana. 
POSSIBILITY OF INCREASE OF AREA OF SPOTTED FEVER. 
The approximate area in which spotted fever occurs has been indi- 
cated in a previous paragraph. Since it has been shown, however, 
that a certain tick (Dermaeentor venustus Banks) is the only known 
agent of transmission o\' the disease in nature, it follows that 
the possible area in which spotted fever may occur i> at Least coin- 
cident with the range of the tick, exactly as the possible range oi 
yellow fever is as extensive as is the area in which the mosquito 
