586 



SCIENCE 



[N. S. Vol. XXXII. No. 826 



necessary for the more difficult task of finding 

 the one, true solution. This combination of 

 speculative ability and the power to do steady 

 toil and even drudgery often under great diffi- 

 culties made him a great investigator and 

 brought him success. 



Some of the experiments devised to lay 

 bare the secrets of the different orders of 

 living things concerned in spotted fever are 

 masterful in their ingenuity and comprehen- 

 siveness, notably those bearing on the hered- 

 itary transmission of spotted fever virus in 

 ticks, on the occurrence of infected ticks in 

 nature, and on the part played by small vrild 

 animals like the squirrel as source for the 

 vvirus. 



Having solved many hard questions he came 

 ito the conclusion that in man spotted fever 

 ••depends simply on the accidental bite by an 

 .adult tick carrying active virus. As only 

 :adult ticks find their way to man and as they 

 • occur only in the spring, the peculiar seasonal 

 prevalence of the disease is nicely explained. 

 'It is almost unnecessary to point out that the 

 "work furnishes clear and direct indications as 

 to what to do in order to prevent the disease. 

 Finally, last year, he discovered the immediate 

 cause of spotted fever, namely, a small bacil- 

 lus, which he found in the blood of patients 

 and in ticks and their eggs. Strains of this 

 baciUus present in ticks from different places 

 vary greatly in morbific power or virulence, 

 and this fact may explain why spotted fever 

 •varies so greatly in severity. 



Many of the observations and discoveries in 

 ■connection with this work have a much wider 

 ^significance, and will surely prove of value 

 and service on the ever-shifting battleground 

 with infectious diseases. 



Rocky Mountain spotted fever in many ways 

 resembles typhus fever. As he was completing 

 his three years' study of the Rocky Mountain 

 disease, having determined its mode of trans- 

 mission, its cause, and a rational method for 

 its prevention, Dr. Ricketts became more and 

 more strongly impressed with the thought 

 which he had had for some time that the 

 special knowledge and training thus acquired 

 would prove of great value in the study of 



typhus fever and thereby perhaps be put to 

 the best use. This idea met with encourage- 

 ment, and in July of last year it was definitely 

 decided to take up the study of typhus fever 

 in the City of Mexico, that being the nearest 

 place, so far as known, where any such work 

 could be done. I speak of this date because 

 I wish to make it clear that Dr. Ricketts 

 reached his decision before and entirely inde- 

 pendently of the establishment by the Mexican 

 government of certain prizes for successful 

 investigation of the typhus fever of Mexico 

 {Tabardillo) . 



Typhus fever (also known as ship fever, 

 camp fever, jail fever, hospital fever) has been 

 one of the great epidemic diseases of the world. 

 Its devastations are recorded on the dark pages 

 of history, the pages that tell of war, over- 

 crowding, want and misery. Until the middle 

 of the last century it prevailed in practically 

 all large European cities; now it has largely 

 disappeared, owing, it is believed, to better 

 sanitary conditions; but it is still smoldering 

 in many centers, and in some places, as in 

 Mexico, typhus in one of its forms now claims 

 hundreds of victims each year. When it as- 

 sumes its most virulent forms typhus fever 

 may become one of the most contagious of 

 diseases, and there is no disease that has 

 claimed so many victims among physicians 

 and nurses. It is stated that in a period of 

 twenty-five years, of 1,230 physicians attached 

 to institutions in Ireland 550 succumbed to 

 typhus. Of the six American scientists who 

 have studied the typhus fever of Mexico since 

 December last three have been stricken and 

 two have died — Conneff, of the Ohio State 

 University expedition, and our Ricketts. It 

 is when the sick are aggregated in hospital 

 wards that the danger of infection is especially 

 great. Until very recently nothing was known 

 as to the cause of typhus fever and the exact 

 mode of its transmission. 



Fully acquainted as a matter of course with 

 all the characteristics of the disease. Dr. 

 Ricketts and his volunteer assistant, Mr. Rus- 

 sell Wilder, began their work in December 

 last. Before many weeks had passed results 

 of great importance were secured; it was 



