356 Col. Sir D. Bruce and others. Tabanide [Dec. 20, 
flagellates. Of the Tabanus thoracinus dissected, flagellates were found in 
the hind-gut, rectum and proctodzeum of 13 (26:5 per cent.). The mouth 
parts and remainder of the gut were negative for flagellates. No Tabanus 
Juscomarginatus were dissected in this series. 
The flagellates found in the hindermost portions of the intestines of both 
these species were similar. Two main types predominated. 
Type 1, Oval, Flagellated Parasites. 
A. Living, Unstained. 
This type is very active, and darts rapidly across the field when free. 
More commonly large masses of these flagellates are seen to be irregularly 
grouped together, the flagella of the outermost ones rapidly vibrating. This 
type divides by longitudinal fission, and forms undergoing this process are 
commonly seen. Bright points can often be made out in the body-substance 
of these parasites (chromatin granules); no definite vacuoles could be seen. 
Masses of these flagellates sometimes occupied a whole field. 
B. Fixed and Stained. 
These flagellates contain a distinct macro- and micro-nucleus. The 
macro-nucleus is large, roughly circular and sometimes diffused. It lies. 
about the centre of the body of the parasite, often occupying its whole 
width. The micro-nucleus is circular or rod-shaped, is placed on the 
flagellar side of and close to the macro-nucleus. The flagellum arises from 
the micro-nucleus, it is short and projects from the body of the parasite, the 
protoplasm of the body being often prolonged for a short distance along the 
flagellum. There is no undulating membrane. Chromatin granules, 
irregular in number and size, are often to be seen in the vicinity of the 
macro-nucleus (Plate 16, figs. 1 to 6). 
Type 2, Circular, Non-Flagellated Parasites, 
These parasites contained macro- and micro-nuclei. The drawing clearly 
indicates their structure (Plate 16, figs. 7 to 14). In the fresh preparations 
they were motionless. 
In the second series of dissections of the Tabanide which had been 
liberated in the fly-compartment of the kraal, 50 TZabanus _ secedens, 
24 Tabanus thoracinus, and 37 Tabanus fuscomarginatus were dissected. 
Of the 50 Tabanus secedens, 2 were infected with flagellates (4 per cent.). 
Of the 24 Tabanus thoracinus, 1 was infected (4 per cent.). No Zabanus 
