358 Tabande as Carners of Trypanosoma pecorum. 
Expt. 2412s. 
July 4, 1910.—White rat inoculated, intra-peritoneally, with the pooled citrated 
contents of the hind-gut, rectum, and proctodeum of two wild Tabanus thoracinus. 
These flies had never been in kraal and were heavily infected with Types 1 and 2 of the 
parasite. 
Result.—Negative. Rat examined for one month after injection. 
CONCLUSIONS. 
1. Tabanus secedens, Tabanus thoracinus, and Tabanus fuscomarginatus 
appeared to be unable to transmit Zrypanosoma pecorum from infected to 
healthy cattle by the mechanical method of transmission. 
2. Owing to the short life of these tabanids in captivity it is impossible, 
from the above experiments, to state whether they can convey the disease 
(Trypanosoma pecorum) after a period of development of the trypanosome in 
the fly. 
3. We believe the three types of flagellates found in Z'abanus secedens and 
Tabanus thoracinus to be various stages in the development of a harmless 
Crithidium in these flies. 
DESCRIPTION OF PLATE 16. 
Smear preparation of hind-gut, rectum and proctodzeum of a Tabanus secedens, stained 
Giemsa, x 2000. 
Figs. 1—6, Type 1, oval, flagellated parasites. Fig. 4 is a dividing form of this type. 
Fig. 1 shows the most common form of this type. Fig. 6 represents an irregular 
mass of the parasites ; these masses often contain very large numbers of the 
parasites. The flagella are poorly stained in these preparations, and so do not 
show up well (Expt. 2412). 
Fias. 7—14, Type 2, circular, non-flagellated parasites. Made from smear preparations 
of the rectum and proctodeum of a Tabanus secedens (Expt. 2411). 
Figs. 15—24, Type 3, elongated, flagellated parasites. Figs. 17 and 18 show the most 
typical forms of this type. Fig. 19 is a stout atypical form, which was not 
common. Fig. 15 represents a form which would appear to be reverting to 
Type 1. Fig. 16 isa dividing form. The parasites figured in Figs. 15—24 were 
obtained from a smear made of the mid-gut of a wild Tabanus secedens which 
had been in the fly-compartment of the cattle kraal (Expt. 2405). 
