SURRA. 411 



immersion) the individual characters were clearly brought out. 

 These were quite sufficient at once to dispel the idea of its being 

 a spirillum. It was obvious that it was a more highly organised 

 micro-parasite, presenting very peculiar and distinctive structural 

 appeaiances. 



" The first glance at the parasites recalled the appearance of 

 nematode ha:'matozoa, as if, indeed, they might be embryonic 

 Filarice ; but when I had carefully studied several specimens, 

 and had further undergone the searching examination entailed 

 by the accurate focussing necessary to obtain a number of sharply 

 defined photo-micrographs, I came to the following conclusions : 



" The somewhat tapering central portion or body of the 

 parasite is continuous at one end with the whip-like lash, and 

 at the other end terminates in an acutely pointed stiff filament 

 or spine-like process. Here and there, possibly from injury or 

 want of development, the spine-like process appears to be 

 blunted or absent. By carefully focussing on the upper edge of 

 the central portion, I discovered the existence, much more 

 markedly in some of the parasites than in others, of a longitudinal 

 memhrane, with either straight or undulating margin. The 

 membrane is attached along the body, arising from the base 

 of the ri^id filament, and becomes directly continuous at the 

 opposite end with the flagellum. In some cases the edge only is 

 deeply stained, giving the appearance of a thread continuous ivith 

 tlic flcigcllum, so that one might be easily led to overlook the 

 membrane, and imagine that the flagellum arose from the 

 opposite end of the body, at the base of the spine-like process. 



" Close to the base of the spine-like process, a clear unstained 

 spot is in many parasites easily distinguished, and at tlie 

 opposite end there is in some the appearance of the deeply 

 stained protoplasmic contents having contracted within the 

 faintly stained membranous investment. Where the longitu- 

 dinal membrane has a wavy outline the undulations are much 

 more marked in some cases than in others. Here and there the 

 wavy outline appears first on the one side of the central portion 

 and then on the other, but there never is any wavy outline on 

 both sides of the same part of the body ; and this was explained 

 by careful examination, which showed that in dying the some- 

 what ribbon-like parasite had become doubled on itself. The 

 discovery of this undulating membrane at once suggested to my 



