In previous papers the morphology of this trypanosome and its action on animals were described. The chief object of this paper is to compare the development of this species of trypanosome with that of the trypanosome causing disease in man in Nyasaland—the T. rhodesiense of Stephens and Fantham. The development of the latter has already been described. It will therefore only be necessary here to present the various data in the form of tables and figures, which can then be compared with similar tables and figures in the previous paper. The Development of T. brucei, Zululand Strain, 1913, in G. morsitans. Seven experiments were made with laboratory-bred flies. Three of these were positive and four negative. Two experiments were also made with wild flies, both of which were positive.

The following experiments were undertaken to find out whether the Naturally Infected Dog strain of the trypanosome causing disease in man in Nyasaland would protect against the other strains. These different strains have been described in previous papers as the “ Human,” the “ Wild Game,” the “Wild Glossina morsitans ,” “Zululand, 1913,” etc., and here they will be known by the same names. “ Human ” will therefore mean a strain of this species of trypanosome coming from man, “ Wild G. morsitans ” from a tsetse fly, and so on. These immunity experiments were necessarily one-sided, as it was, with three exceptions, only animals which had recovered from the weaker Naturally Infected Dog strain which were available.

In July, 1912, Dr. A. Theiler, C. M. G., Director of Veterinary Research (Union of South Africa), Pretoria, sent this Commission several blood preparations taken from horses and dogs supposed to be suffering from nagana. Much to the surprise of the Commission, a large percentage of these trypanosomes showed posterior-nuclear forms. This disposed of the contention that the so-called Trypanosoma rhodesiense could be distinguished from other species of trypanosomes by this peculiarity, and first led the Commission to suspect that T. rhodesiense was in reality T. brucei . Dr. Theiler was then asked to send the living strain through to the Commission in Nyasaland, and this, after several failures, was at last successful.

Glossina brevipalpis (Newstead) is found at many spots along the west shore of Lake Nyasa. The nearest point to the Commission’s camp at Kasu where they were at all common was at the mouth of the Lingadzi river (13° 27' S. lat., 34° 19' E. long.). This was 50 miles away, but with the aid of a motor-cycle specimens of these flies were brought up to the camp. It is proposed in this paper to give: (I) a short account of the habits of this tsetse fly; (II) the results of the dissection of the flies; (III) the infectivity of the wild flies; and (IV) the result of various transmission experiments.

In a former paper five strains of this species of trypanosome, obtained from man, were described. In this it is intended to describe another set of five. A small quantity of blood was taken from the sick native, brought up to the laboratory, and inoculated into a monkey or white rat. Strains VII, VIII, and X were directly inoculated into the rat from which the drawing and measurements were made; in strains VI and IX a single monkey intervened. These five stains have therefore been obtained under fairly similar circumstances, and should prove useful for purpose of comparison. This is put in tabular form in table. I, and the histroy of the previous five strains in also given, as this was omitted in the former paper. It is possible that the type of a strain may be changed by passage through different animals before it reaches the rat.

In previous papers the morphology of this trypanosome and the susceptibility of various animals to its pathogenic action have been described. In this is given an account of its development in Glossina morsitans . In Uganda the study of the development of Trypanosoma gambiense in G. palpalis was much assisted by the circumstance that large numbers of laboratory-bred tsetse flies were available. This was due to the fact that the pupæ of G. palpalis could be collected on the lake-shore in practically unlimited numbers. It is quite otherwise with G. morsitans . It has been found impossible to find the pupæ of this species in any numbers, so that all laboratory-bred G. morsitans have had to be hatched out of pupæ obtained from captive flies, a slow and laborious process. The flies are caught some 20 to 30 miles from the laboratory and brought up to Kasu camp by a native on a bicycle. This kills a large number of the flies. Moreover, the climatic conditions at the camp are not always favourable for breeding and hatching out. This was remedied to some extent by establishing a breeding station down in the low-country, but as this had to be left in the charge of natives the results were not always very satisfactory.

Five hundred flies, freshly caught in the Proclaimed Area, were killed by chloroform and the gut of each was roughly dissected out, smeared on a slide, fixed by osmic vapour and alcohol, and subsequently stained by Giemsa. The flies were all caught in the bush, away from the paths, the fly-boys proceeding in single file and catching the flies with gauze nets as they circled round, or settled on the boys or the grass. The proportion of male flies to females caught was roughly two to one. But only 30 females were used in the present experiment, the majority being sent to the breeding-station at Chunzi.

This strain was obtained in the “fly-area” of the Upper Shiré Valley, in the Liwonde district, which is situated about 100 miles south of the “Proclaimed Area.” At the time it was procured no cases of trypanosome disease in man had been reported from this district; lately, a case has been discovered at Mpimbi, in the south of the district, about 150 miles south of the “Proclaimed” or Sleeping Sickness Area. Three dogs infected with the wild Glossina morsitans strains of this trypanosome were brought to Kasu, and other animals―monkeys, dogs and rats―were inoculated from them.

The object of this paper is to attempt to set up a rough standard of the proportion of infected to non-infected tsetse flies in an ordinary “fly-area” where wild game abounds. It is thought that a standard of this kind may prove useful in the future. The flies were collected in the low country lying near the Commission’s camp at Kasu, in what is known as the “Proclaimed” or Sleeping-Sickness Area of Nyasaland. This bit of country swarms with Glossina morsitans and wild game, the latter highly infected and well protected.

In a previous paper the morphology and action on animals of this species of trypanosome were described. In this is given an account of its development in Glossina morsitans . Trypanosoma caprœ belongs to the T. vivax group, in which the development of the trypanosomes is restricted to the proboscis.

In a previous paper the morphology of this species of trypanosome and its action on animals were described. In this it is intended to give an account of its development in Glossina morsitans . This trypanosome belongs to the group in which the development takes place first in the gut, then passes forward into the labial cavity of the proboscis, and finally reaches the hypopharynx, where the trypanosomes revert to the original “blood-forms” and become infective. There is no infection of the salivary glands.

In June, 1913, one of the members of the Commission went to the Liwonde district to identify and isolate the various species of trypanosomes infecting the “fly” and wild game in the “fly-belt” which extends along the Upper Shire River valley from Lake Pamalombe to the Murchison cataracts. This “fly-area” is, roughly speaking, 100 miles south of Kasu and the “Proclaimed Area.” It is separated from the extensive “fly-area” of the plains on the west shore of Lake Nyasa, of which the “Proclaimed Area” forms a part, by a range of hills and high plateaux where the “fly” is absent, although there is nothing to prevent trypanosome-infected wild animals wandering from one “ fly-belt ” into the other. The valley of the Upper Shire is thickly populated, and the “fly-area” is crossed by two of the most frequented roads in Nyasaland, the grand trunk road running from Zomba to the north and the main road from Liwonde to Fort Johnston. Although thickly populated, human trypanosome disease, though probably existing, has not yet been discovered in this district. The natives, however, can keep no cattle, and their goats and dogs are constantly destroyed by trypanosome diseases, so that they have to continually import these animals from the highlands.

In Previous papers the morphology of these strains of trypanosomes was described, and it was concluded that they are identical with the try-panosome causing disease in man in Nyasaland, the Trypanosoma rhodesiense of Stephens and Fantham, the T. brucci of this commission. This paper tabulates the action on animals of the two strains, and they are compared in this respect with each other and with the Human Strain.

The object of this paper is to put on record the proportion of tsetse flies found in this district of Nyasaland to be infected with disease-producing trypanosomes, and, further, to identify the species of trypanosomes with which the flies are infected. It must be understood that this paper only deals with the district lying near the camp at Kasu and not to every part of Nyasaland. The geographical position and other features of this district have already been described in a previous paper. It is known as the "Sleeping Sickness Area" or "Proclaimed Area", and in it almost all the cases of the Human Trypanosome Disease of Nyasaland have occurred. This disease is caused by Trypanosoma rhodesiense , and the natives give it the name of "Kaodzera," but there is good deal of evidence accumulating that T. rhodesiense is in reality T. brucei , in which case the disease would be known as "Nagana."

In previous papers the morphology of various strains of this trypanosome—from man, wild game and wild Glossina morsitans —was described, and the different strains compared. This paper describes the action on animals of the five strains derived from cases of trypanosome disease in man in Nyasaland, and compares their virulence. In a future paper it is proposed to describe in the same way the action on animals of the Wild-game and Wild G. morsitans strains, but up to the present this has been impossible on account of the scarcity of experimental animals.

In a previous paper the morphology of this interesting species of trypanosome was described, and it is now proposed to give an account of its action on animals. One of the first interesting points to be noted about this species is that, as far as is known, the warthog ( Phacochœrus œtheopicus ) is the only animal among the wild game of this district which harbours it. It is probable that it will also be found in the blood of the bush-pig, but not a single specimen of this animal has as yet been obtained by the Commission. The warthog is numerous in the low country in this neighbourhood, which accounts for the large number of tsetse flies found to be infected with Trypanosoma simiœ .

The chief object of this Commission in coming to Nyasaland was to inquire into the relation of the African fauna to the maintenance and spread of trypanosome disease. The Commission arrived at their camp on Kasu Hill on January 12, 1912. As this was the rainy season the low country was covered with dense vegetation and much of it under water. Nothing could therefore be done in the study of the fauna until about the beginning of June, when the dry season was well established.