WORK UPON WHICH BULLETIN IS BASED. 
ments however, were with adult ticks. It was found that when an 
St becomes infected with the disease, the infection passes through 
t t eggsT-loped in the tick, so that the young of the next genera- 
tion may transmit the disease. 1 
ThTmain points determined by Dr. Ricketts are as follows 
(1) Guinea piss and certain other animals, as monkeys, are sua- 
•^SSSSttSS- to an infected ammal contract the infec- 
tion and are able to transmit it to the following or nymphal stage 
(3) Nymphal ticks feeding upon infected animals acquire the 
r^mvpr of transmitting the disease as adults. 
V U) AdultUcks arf able to acquire the disease by feeding upon an 
infected animal and to transmit it through the egg stage to the sue- 
ceeding generation. 
(5) Infective ticks are to be found in nature. 
it transmission of disease organisms through the egg stage of 
tick is known in a number of other instances. It is the case with 
Ztick Margaropus annulatus Say, which transmits splenetic fever 
o c tt e in the southern portion of the United States. The causative 
or 4nimo splenetic fever has actually been found m the eggs of 
tl fs 1 1 Dr Ricketts recently made a tentative announcement of 
finding of the spotted-fever organism in the eggs of Decent* 
ZZL Bank. Future investigation will undoubtedly result m 
C 1r?ofXtS SKt—d by D, Ricketts were corr*. 
rated about the same time by Dr W. W. King, of ^^ah* 
and Marine-Hospital Service, whose results were published in the 
Public Health Reports of July 27, 1906. 
WORK UPON WHICH THIS BULLETIN IS BASED. 
The work of the Bureau of Entomology on the spotted-fever 
tick began in 1908, when the investigation of the life history and 
habits of the species was undertaken. Plans were made for deter- 
mining the distribution of the tick and for the exhaustive htc-lns- 
torv investigations necessary in the formulation oJ plans of con- 
trol. Following the plan for determining the distelbutlOl. of the 
lick, (wo men were selected, one to travel through the southern 
Rocky -Mountain region and the other through the northern. 1 he 
late Mr. F. C. Pratt made investigations in New Mexico, Arizona, 
southern California, and Colorado. Mr. W. Y. Knig, whose work 
lgen t of the bureau began July 1, 1909, made the investig 
distinct stages, namely, egg, i.m>.. • ?'•';•■ ,.,,„„ „„, eggs ate „,„,„■ 
legged animals A., . eeaii >- < Tlu , h w:lits mllil „ ulu 
ESZTSZJZSSS. :.'-. »- »» ft* ana to adult 
8464°— Bull, ion— 11 2 
