DECEMBER 10 1903] 
IVATRO RLS 
123 
It is not clear, however, that the statement of 48 
candles per cubic foot would not be equally mislead- 
ing, as the light emitted from good acetylene burners 
varies enormously with the rate at which the gas is 
consumed, so that with small burners the illuminating 
value of the gas is rarely more than 20 candles a foot, 
whilst with 1-foot burners it is a remarkably good 
burner that gives 42 candles per cubic foot of gas 
consumed, 
In referring to the formation of carbonaceous 
growths at the burner tips, the authors point out that 
although this has been put down to the action of heat 
on polymerisation products in the acetylene, yet that 
if this were the case the trouble should disappear 
entirely if the gas were washed with heavy oil before 
entering the burners, this procedure, however, not 
giving entire freedom from the trouble. In this 
criticism, however, they evidently overlook the fact 
that not only does polymerisation of the acetylene take 
place where there has been undue heating in the 
generator, but that no matter how thoroughly the gas 
may be purified before reaching the burner, a further, 
though small, polymerisation will take place in its 
flow through the heated steatite tips at which it is 
burning, and that the trace of benzene so formed is 
quite capable of giving the trouble. 
"The practical details given as to size of pipes and 
other points upon which little or no knowledge exists 
amongst generator makers are of the greatest value, 
and the book may be most heartily recommended to 
all interested in the production and use of acetylene. 
THE TSETSE FLIES. 
A Monograph of the Tsetse Flies (Genus Glossina, 
Westwood). Based on the Collection in the British 
Museum. By E. E. Austen, with a Chapter on 
Mouth-Parts by H. J. Hansen, Phil. Doc. Pp. 
ix+319. (London: Printed by Order of the 
Trustees, 1903.) Price 15s. 
See fifty years ago J. O. Westwood gave a |} 
description of a ‘‘ destructive species of dipterous 
insect known under the name of Tsetse,’’ and referred 
it to the genus Glossina, first established twenty years 
previously by Wiedemann. From that time onwards 
references to the tsetse fly and its association with 
a mysterious disease fatal to horses, cattle, and other 
animals become very numerous in the writings of 
travellers and naturalists, and various were the 
theories propounded to explain the relation of the fly | 
to the disease. Drysdale, in 1879, seems to have been 
the first to suggest that the tsetse fly disease might 
be of an infective nature, the infecting agent being con- 
veyed by the bite of the fly. In 1895 and 1897 the 
well-known reports of Lieut.-Colonel Bruce appeared. 
He described the tsetse fly disease or nagana met 
with in Zululand, and established the fact that it is 
due to a protozoan blood parasite, the Trypanosoma 
Brucet, which is conveyed by the bites of the tsetse 
fly from affected to healthy animals. As horses and 
cattle are unable to exist in the districts inhabited by 
the fly, the problem of transport in these ‘ fly belts ”’ 
is a serious one, and the tsetse fly and its distribution 
NO. 1780, VOL. 69] 
have assumed great economic importance. In India 
and Burma there is a similar, if not identical, disease 
known as surra, which is also conveyed by a biting 
fly, perhaps a species of Stomoxys. 
Within the last few months evidence has been 
accumulating, through the work of Castellani, Bruce 
and others, that sleeping sickness, the ravages of 
which have assumed alarming proportions, may be 
caused by a trypanosome (T. Castellanit) attacking the 
central nervous system (see Nature, vol. Ixviii. p. 
116). 
From analogy with nagana and other facts (see 
Nature, vol. Ixix. p. 34) it would seem probable that 
a tsetse fly conveys the infection in this disease, and 
therefore that measures of prevention and extermin- 
ation directed against the fly might stamp out sleep- 
ing sickness. Other diseases also, e.g. trypanosoma 
fever, are caused by species of trypanosomes, and 
these, too, may very likely be conveyed by tsetse flies.* 
In view, therefore, of the practical importance of 
an accurate knowledge of the genus Glossina, the 
Trustees of the British Museum have been well advised 
to publish this monograph upon the tsetse flies, the 
preparation of which has been entrusted to Mr. Austen. 
We may say at once that Mr. Austen has produced 
a work which must for some time remain the standard 
one upon the subject. He gives both a popular and 
a scientific description of the flies, a full bibliography 
with copious abstracts, the whole being illustrated 
with many figures in the text, with a map showing 
the geographical distribution, with beautiful coloured 
plates of the seven known species from drawings by 
Signor Terzi, and with two plates of the mouth-parts 
of Glossina and Stomoxys. The latter, together with 
a description, are by Dr. Hansen, and will enhance 
the value of the volume to the dipterologist. 
* In the first place it is to be noted that, although the 
term ‘‘ the tsetse fly’ is usually employed, there are 
at least seven species, so that ‘‘tsetse’’ becomes a 
generic rather than a specific name. By some the 
original Glossina morsitans has been called the ‘‘ true 
tsetse.’? The name “tsetse’’ is of obscure origin, 
but is certainly onomatopoetic, derived from the 
peculiar buzzing sound made by the fly on the wing. 
The tsetses are confined to Africa, are always met 
with in the neighbourhood of water, and are often. 
restricted to peculiarly well-defined tracts of country. 
Mr. Austen’s description of them may be reproduced 
here, since NaTtuRE may reach many who may not 
have access to this monograph :— 
““The tsetses are ordinary-looking sombre brownish 
or greyish-brown flies varying in length (excluding the 
proboscis) from 33 to 4% lines (73-10 mm.) in the case 
of Glossina morsitans to about 54 lines (113 mm.) in 
the case of Gl. fusca or longipennis, with a prominent 
proboscis in all species. The hinder half of the body, 
or abdomen, in the best known species, though not 
in all, is of a paler colour and marked with sharply 
defined dark brown bands, which are interrupted on 
the middle line; the abdomen, however, is invisible 
when the insect is at rest, as it is then concealed by 
1 Since the above was written, a further report, on sleeping sickness by 
Col. Bruce has been issued. In this much additional evidence is given of 
the correctness of these views of the nature of sleeping sickness and of its 
transference by a tsetse. Trypanosoma fever may be the early stage of 
| sleeping sickness. 
