NOTES ON SOME TROPICAL DISEASES 31 



as it passes, after causing a decrease of population of the 

 affected tracts.' 1 The sporadic form, miscalled ' malarial cachexia,' 

 has been known for centuries, being marked by persistent fever 

 of an alternating, remittent, or intermittent type. It was often 

 mistaken for typhoid in the earlier remittent stages, but subsequently 

 distinguished by the great enlargement of the spleen and later of the 

 liver, with extreme wasting of the rest of the body and chronic illness, 

 ending commonly in some fatal complicating illness. 



Our knowledge of the cause of the black-fever begins with the 

 discovery of the ' Leishmann-Donovan ' body, first described by 

 W. B. Leishmann 2 as probably an involution form of a human try- 

 panosome. This observation was abundantly confirmed by Manson, 

 Ross, and Christophers, among others. 



Soon after, J. H. Wright, of Boston, 3 published an account of 

 quite similar bodies in Delhi boil, a local skin affection, and met 

 with in the Punjab, 4 in India. These bodies are round and oval, 

 2 to 3 millimetres in diameter, the size of blood-platelets, and con- 

 taining a nucleus and a smaller body (kinetonucleus). They 

 multiply mainly in the large endothelial cells (macrophages), especi- 

 ally of the spleen and bone-marrow. The host-cells ultimately 

 rupture, and allow the parasites to escape, some of them entering the 

 circulating blood. 



The true nature of these bodies has been fully established by the 

 work of L. Rogers. 



Rogers obtained by spleen-puncture a little blood containing 

 these bodies, and added to this i c.c. of sterile salt solution containing 

 a little citrate of soda, 5 in order to prevent coagulation, and to 



1 L. Rogers, the first Milroy Lecture, 1907, Brit, Med. Journ., February 23, 

 1907. where the history and symptoms of the disease are given. 



2 Leishmann, ' On the Possibility of the Occurrence of Trypanosomiasis in 

 India,' Brit. Med. Journ., May 30, 1903 ; also Donovan, ibid., July n, 1903. 



3 J. Homer Wright, Journal of Medical Research, December, 1903. 



4 From the fact that kala-azar is unknown in the Punjab, Rogers points out 

 that the parasites of Delhi boil are probably not identical with those of kala-azar. 



5 Rogers found that acidifying the medium with a trace of citric acid favoured 

 the life of the parasites, increasing the rate of growth and multiplication. 



