East Coast Fkvkh IDS 



here lune for nisiny y*^'*^»'^ abamlonefl cattle rearing on account of the 

 raidinii propensities of the Masai and other tribes,'' from wliich it would 

 appear that the acti\it\' of the Masai and other raidei-s at that time 

 nuist have ert'ectually prevented the spread of the disease from the coast 

 to tlie interior. 



In this preliniinaiy report Koch expresses his intention ')f 

 carrying out certtiin experiments at tlie first opportunity for the pur- 

 pose of confirming those of the American <:)bservers regarding the 

 •communicabihty of the disease by the medium of ticks ; and in a later 

 report, dated 12th February, 1S98, he recounts the experiments whicli 

 he carried out in the Usambara Mountains with tlie larval progeny of 

 ticks taken from apparently healthy ajiimals and from a calf suffering 

 from Texas fevei-, whose bhjod contained a very large number of Texas 

 fever parasites, Ijut oidv that form described in his previous commui}i- 

 cation as the first form of the paiasite — that is to say, the forms re- 

 sembling miniature staves ami those resembling a willow leaf. These 

 larxal ticks lie placed on four healthy oxen from the interior, two 

 i'ecei\ ing the progeny of the ticks taken from the apparently healthy 

 minimal, and two the larval ticks from the sick calf, both lots of animals 

 being kept apart from each other. As a result of this experiment, 

 Koch records that on the twenty-second day after the ticks had 

 been placed on the cattle an analysis of the blood of the two animals 

 upon which the progeny of the ticks from the sick calf had been placed 

 showed for the first time embedded in the red corpuscles specimens of 

 P}jro!^oma bu/emianni in that most extraordinary characteristic pear- 

 shaped form of the full-grown parasite, while the two animals upon 

 which the progeny of the ticks of the healthy coast cattle had been 

 placed remained healthy. ^ Both these infected animals recovered, and 

 from the blood of one of these animals four other healthy animals 

 received a subcutaneous injection of 20 c.c. each. These animals 

 .sickened in turn, but like the animals which forjued the subject of 

 the fii-st successful experiment, pyriform organisms only were found 

 in their blood. This experiment was repeated again with blood from 

 one of the sick animals, and again the experimental animals contracted 

 the disease in a mild form, and here Koch's record of experiments 

 cea.ses, and at the close of his repoi't he observes that he has not 

 succeeded in reproducing the severe and very fatal form of Texas fever 

 which he had observed on the coast, but that he has caused six of the 

 strongest experimental oxen which were artificially infected in the 

 interior to be taken down to Dar-es-Salaam and placed on an infected 

 pasture there together with some fi-esh non-immune cattle obtained 

 from Pugu. 



Koch's obser\'ations appear to have gone no further at this 

 time, or if they did they were not considered of sufficient interest to 

 place on record. How unfortunate this omission pro^■ed to be to 

 South Africa we now know, as, if the projected experiment had been 

 carried out and the results noted, he might have found out that the 

 disease which he produced in the Usambara Mountsiins was not the 

 rapidly fatal form of the disease whicli killed off animals so quickly at 



n2 



