292 Dr. L. Rogers. Development of Hepatomovm of [Oct. 16, 



from the body by means of ulcers sometimes found in the intestines, the 

 granulation tissue -f which contains the parasites, and they may thus 

 reach water. Apart from the great rarity of such infected intestinal lesions 

 in my very extensive post-mortem experience of this disease in Assam and 

 Calcutta, the fact that sterility is essential for the continued development of 

 the flagellated stage of the organism appears to me to make this mode of 

 infection an exceedingly improbable one. Moreover, I have been unable 

 to obtain any development of the organism in even sterile water kept at the 

 most favourable temperature, while even in sterile acidified water similar 

 negative results have recently been obtained. 



Relationship of the Optimum Temperature for the Development of the Flagellate* 

 to the Seasonal Incidence of Kala-Azav and Cachexial Fever. 



If the conditions I have found necessary for the development of the 

 flagellate stage of the Hepatomonas of kala-azar afford any indication of the 

 natural conditions under which it occurs, then the striking fact that the 

 relatively low temperature of about 22° C, or 72° F., is essential to the 

 process, would indicate that infection is only likely to take place in India 

 during the colder part of the year. Owing to the fever in this disease 

 lasting for many months, or even several years, with long intervals of little 

 or no rise of temperature, while cases not infrequently begin very insidiously, 

 patients presenting themselves with marked, but often unsuspected, enlarge- 

 ment of the spleen, and a history of only a few days' fever; it appears 

 probable that the incubation period may be a long one, and the onset very 

 insidious and indefinite. Nevertheless a clear history can often be obtained, 

 and an analysis of the notes of a number of cases showed five times as 

 many in which the symptoms fh*st commenced in the six months from 

 November to April as in the remaining six hot months of the year, so that 

 the cold weather months, together with the very commencement of the hot 

 weather, to allow for the probable incubation period, show a very marked 

 preponderance of the infection. Moreover, Dr. Dodds Price, of Assam, 

 informs me, as a result of Ins unique experience of kala-azar, extending over 

 15 years, that every case he has seen in Europeans began in the cold season, 

 and that among his hundreds of native cases .he has noticed the same marked 

 tendency for definite symptoms of the disease to first show themselves at 

 that time of the year. The practical importance of this point in relation 

 to the prevention of the disease is evident, while the close agreement of its 

 seasonal incidence with the deductions from my experimental data is of 

 considerable interest. It is also worthy of note that this disease is most 

 preA^alent in just those parts of India where the temperature conditions for 



