260 EELATION OF TSETSE TO PARASITE. 



which is carried by ticks, and especially upon the different 

 forms of malaria lend the greatest probability to the 

 conclusion, that each of these blood-diseases can be carried 

 only by a perfectly definite kind of blood-sucking insect 

 (human malaria by Anopheles, bird malaria by Culex, 

 Texas fever by the tick, recurrent fever by bugs, and so 

 on), and that in this intermediate host the organism that 

 occasions the disease passes through a special stage of 

 development, which appears generally to be a sexual 

 reproduction.* 



" Now since in South Africa experiments have 

 furnished incontrovertible proof that the Trypanosoma- 

 disease is carried by the Tsetse-fly, the bite of which had 

 long been dreaded as being fatal ; since on the other hand 

 the same disease occurs here ; and finally seeing that the 

 true Tsetse-fly has been observed here, it is justifiable to 

 conclude that it is highly probable that in our colony 

 also Surra is carried, and, moreover, exclusively carried 

 by this one fly, the Tsetse. The fact is that, in the case 

 of all these blood diseases, the host and intermediate host 

 are animals of perfectly definite kinds. It is, moreover, 

 improbable that the proboscis f of the Tsetse merely 

 operates as an inoculating-needle ; rather must we assume, 

 from analogy with malaria, that within the fly the Trypa- 

 nosoma passes through a special stage of development, 

 which it is true is at present unknown" (pp. 137-138). 



Numbers of Tsetse-flies, which were identified as speci- 

 mens of Glossina morsitans,Westw., wei'e found on Feb. 18 

 and 19, 1900, on the road from Kilwa to Barikiwa : the 

 weather at the time was thundery and rainy (p. 138). 



Notes on the genus Glossina, and on Stomoxys calci- 

 trans, with woodcuts of the latter and its transformations 

 (after Howard) (pp. 138-141). At the bottom of p. 139 

 the development of the Tsetse is stated in error to be still 

 entii'ely unknown. Pages 141 to 146 are devoted to a 

 description of Glossina morsitans, based upon an examina- 

 tion of three specimens taken near Kilwa, as, mentioned 



* It should be noted, however, that the host in which a parasite 

 becomes sexually mature is the definitive and not the intermediate one. 

 Thus in the case of festivo-autumnal fever Ancrphcles is the definitive and 

 man the intermediate host of Laverania prxcox. — B. E. A. 



t The word in the original is Stick, meaning literally "stab" or 

 " puncture."— E. E. A. 



