32 PROTOZOA AND DISEASE 



enable him to examine it frequently for the purpose of noting any 

 changes in the parasites. The first observations were made at 

 blood-heat, and produced negative results. Repeating the observa- 

 tions with blood kept in an ice incubator at 22 C., Rogers found 

 that not only did the parasites multiply rapidly, but they also 

 increased in size, and developed a protoplasm that stained blue with 

 Leishmann's modification of Romanowsky's stain ; after a time a 

 development of actively motile flagellated forms took place. Some 

 of the chief forms described by Rogers are shown in Fig. 8. For 

 further details the original papers l should be consulted. 



The general effect of the disease on the patient's blood is to 

 produce a pronounced anaemia. Rogers, among other blood changes, 

 has found a great reduction in the number of polynuclear leuco- 

 cytes, which may fall as low as 500 to each c.cm. So great a reduc- 

 tion he regards as almost diagnostic of kala-azar, so much so, in his 

 opinion, that for diagnostic purposes it may replace spleen-puncture, 

 which is dangerous in extreme anaemia. 



The manner in which the disease is spread has not yet been fully 

 worked out. Death is usually preceded by ulceration of the intes- 

 tines, and many parasites must be voided with the excreta. It is 

 very probable that an intermediary host is necessary, as is the case 

 in other flagellate diseases. Some recent observations 2 tend to show 

 that the common bed-bug may be the intermediate host of the 

 Leishmannia Donovani. 



It would thus appear that the protozoa of kala-azar differ from 

 the trypanosomes in that they lack an undulating membrane. In 

 this they resemble the simpler flagellates, such as the herpetomonas 

 of the common house-fly and similar forms that occur in other 

 insects. 



1 L. Rogers, note in Brit. Med. Journ., July 2, 1904, p. 29 ; Chattergee and 

 Rogers, Lancet, May 15, 1906; Milroy Lectures, Brit. Med. Journ., March 9, 

 1907. See also L. Rogers, Proceedings of Royal Society, 1906, and the Quarterly 

 Journal of Microscopical Science, vol. xlviii., part iii., pp. 367-377. 



2 See a paper by W. S. Patton on 'A Species of Hcrpetomonas found in Culex 

 Pipiens] Brit. Med.Journ., July 13, 1907. 



