STUDY OF TSUTSUGAMTJSHI DISEASE. 5 



bright red or orange in color and is found on land that has been sub- 

 merged by flood. Here it is best collected by tying a monkey out over 

 night or by catching the field mice (Arvicola hatanedzumi Sasaki) oc- 

 curring in such regions. The insects collect in groups on or about the 

 eyelids of the monkey, while they are always found attached in large 

 numbers to the inner surfaces of the ears of the mice. Mites resembling 

 these in size and color occur in many parts of Japan, but they do not 

 attack persons. • The akamushi of other than infected regions do not 

 transmit disease. 



Several supposed causative organisms have been described for the 

 infection, the latest and probably the one calculated to excite most 

 interest being Ogata's plasmodium. None of these alleged discoveries 

 has been confirmed, and judging from what we heard and such blood 

 examinations as we could make in Japan, it appears that Ogata's Plasmo- 

 dium does not exist. The causative organism is as yet unknown. 



Spotted or tick fever of Montana, as known by Wilson and Chowning, 

 Anderson, Stiles, Eicketts and Ashburn, also occurs in very strictly 

 limited areas, particularly in a strip of country about 4 to 10 miles 

 wide and 50 miles long, lying on the west side of the Bitter Root River 

 and the eastern side of the Bitter Root Mountains and partly on the 

 slopes of the latter. The country in question has a considerable fall 

 of snow which remains on the mountains until mid June and on the 

 highest peaks for two or three weeks longer. The Bitter Root River is 

 largely fed from this snow and, as it begins to melt in March and 

 continues to do so with increasing rapidity until most of it has dis- 

 appeared, the stream is in a state of freshet during this time and does not 

 again reach "low water" until July. ' During the same period ticks (Der- 

 macenter occidentals), which before and after these freshets are infre- 

 quently seen, appear in great numbers, particularly in the forests, thickets 

 and uncultivated regions, and they are very apt to get on any person or 

 animal going into such parts. Cases of "spotted" or "tick fever" like- 

 wise, and as rule, appear during the same period, and in almost all 

 instances of infection a history of a recent visit to, or residence in, the 

 infected district, and in many cases an account of tick bites received 

 there, is given. Wilson and Chowning identified the. tick as the carrier 

 of the disease as early as 1902. Ashburn, after a study of all the cases 

 occurring in 1904 and most of those in 1905, came to the conclusion 

 that a considerable proportion of these cases gave neither history nor 

 signs of tick bite and, for that and other reasons which it is not necessary 

 to detail here, agreed with Stiles that the tick was not concerned in 

 transmitting the disease. However, the more recent and very excellent 

 work of Ricketts and of King, and their apparent success in transmitting 

 the infection to monkeys and guinea pigs by means of the tick, seem to 

 indicate that Wilson and Chowning were right in their belief as to the 

 method of transmission. It may therefore be said that the disease is 



