380 



Dr. H. L. Duke. Relation of Fowls and [May 9, 



the fly. The connection between T. gallinarum and these crithidise was 

 further established on several occasions by the subsequent discovery of the 

 trypanosomes on repeated examination of the cock's blood. Owing to the 

 extreme difficulty of making certain that any given fowl was not infected 

 with this trypanosome, it was not found practicable to conduct any 

 systematic experiments on its development in G. palpalis. The actual day 

 of development of any given infection cannot be established, as in every case 

 the flies were a considerable time on the infected cock. 



Although the blood of all the fowls employed was examined on numerous 

 occasions, T. gallinarum was not always to be found in those birds which 

 were proved by fly-dissection to be infected. The trypanosomes are very 

 rare in the peripheral circulation, and even on centrif legalisation of consider- 

 able quantities of blood after death were only obtained in very small 

 numbers. 



The preceding tables show the cycle and other experiments in which these 

 crithidiae were seen in the course of the fly-dissection. In Table I the flies 

 were fed upon infected cocks only. In Table II the flagellates were found 

 incidentally in the course of cycle-experiments with T. gambiense. 



The following Description of the Morphology of the Flagellates has been 

 most kindly drawn up for me by Miss Eobertson, to whom all positive flies 

 were handed over : — 



"In many respects the appearance of T. gallinarum in G. palpalis is 

 exceedingly characteristic. The infection is rarely very numerous, seldom 

 assuming anything like the virulence of T. gambiense or T. nanum in the 

 same situation. 



" The trypanosomes are, as a rule, situated pretty far back in the 

 alimentary tract. The mid-gut of the fly, that is to say, the region 

 between the proventriculus and the origin of the Malpighian tubules may 

 conveniently be divided into three portions, anterior, middle, and posterior. 

 The infection very rarely proceeds further forward than the middle portion. 

 On one occasion only were these trypanosomes found in the anterior portion 

 and ip the proventriculus. 



" The motion of the flagellate in the live state is very striking, and at 

 once arrests the attention of any observer accustomed to the appearance of 

 gut-forms of mammalian trypanosomes. The body is in the vast majority of 

 the forms quite stiff through about two-thirds of its length, and is often 

 broad and relatively massive, though the breadth is subject to variation. 

 The flagellum is much thicker than in mammalian trypanosomes, and has a 

 lashing motion, which drags the organism forward with a rapid movement 

 of translation. This progression takes place in straight lines, and in the 



