50 
NATURE 
[SEPTEMBER II, 1913 
the human trypanosome, T. rhodesiense, its wide dis- 
tribution in south Central Africa, its occurrence in 
wild game and domestic stock, and its transmission by 
Glossina morsitans. The authors affirm emphatically 
that the fly does not become infective until the try- 
panosome has invaded its salivary glands, an event 
which is the second and final act of a developmental 
cycle that begins in the gut of the fly. [t was found 
that the first portion of this cycle could proceed at 
lower temperatures (60°—7o° F.), but that for its com- 
pletion higher temperatures (75°—85° F.) are essential. 
The parasites can, however, persist in the fly at an 
incomplete stage of their development for at least sixty 
days under unfavourable climatic conditions. Several 
species of trypanosomes, some old, some new, are 
described from wild game or domestic stock; remark- 
able among the new species is a large form of the 
ingens-type, to which the name T. tragelaphi is 
given, found in the blood of the sitatunga, Limno- 
tragus spekei. 
Tue problems connected with tsetse-flies and the 
parasites of man and animals which they unwittingly 
transmit are perhaps the most important questions 
with which European administrators of African terri- 
tories have to deal at the present time, and these 
troublesome insects continue to receive an amount of 
attention which their purely scientific interest would 
never have aroused. In the Annals of Tropical Medi- 
cine and Parasitology (vol. vii., Part 2), Prof. New- 
stead describes a new species of tsetse-fly from the 
Congo Free State under the name Glossina severini; 
and in the same number Mr. Llewellyn Lloyd publishes 
records and photographs of' the breeding-places of 
G. morsitans at Ngoa, on the Congo-Zambesi water- 
shed. The pupz of G. morsitans were always found 
either in association with trees or in holes in the 
ground; in the former case the trees were always 
abnormal or injured. The pupz were never found at 
the base of normal trees or under bushes, and they 
are always deposited in such positions that they are 
not likely to be scratched up by game-birds. In the 
Bulletin of Entomological Research (vol. iv., Part 1), 
Dr. Scott Macfie discusses, with the aid of many photo- 
graphs, the distribution of tsetse-flies in the Ilorin 
province of northern Nigeria, and describes a new 
variety of G. palpalis, with an excellent coloured 
illustration. In the same journal Dr. J. O. Shircore 
describes two new varieties of G. morsitans from 
Nyasaland. 
Tue proceedings of the Orchid Conference held by 
the Royal Horticultural Society in November last are 
reported at length in the Society’s Journal (vol. 
xxxviii., Part 3). They include four papers read at the 
Conference, in the first of which Prof. F. Keeble dis- 
cussed the physiology of fertilisation, with special 
reference to recent investigations by Lutz, Fitting, 
and others, and pointed out that pollination may bring 
about three types of events: (1) fertilisation, (2) 
changes due to contact of pollen with the stigmatic 
surface, and (3) results which may be described as 
intoxications or responses to chemical stimulation. 
In a paper on the application of genetics to orchid 
©, Hurst recapitulated the first 
breeding, Major C. C. 
NO. 2289, VOL. 92| 
| principles of genetics, and pointed out that as regards 
any one heritable character represented by a factor, 
there are three distinct kinds of individual plants— 
homozygous or pure, heterozygous or impure, and 
identification of individual ‘‘stud”’ plants, colour and 
albinism, self-sterility in orchids, &e. 
Ir requires an altogether special equipment, not only 
of exact zoological and historical knowledge but also 
of sympathetic insight into the conditions which pre- 
vailed in the past, to compose such a delightful lecture 
as that which Prof. F. J. Cole, of Reading, has pub- 
lished in the Transactions of the Liverpool Biological 
Society (February 14, 1913). In his crisp and epi- 
grammatic treatment of a series of well-chosen inci- 
dents he has admirably brought before us “the early 
days of comparative anatomy,” and the feeling of 
most readers, and especially those who from their 
personal experience realise how difficult such know- 
ledge is to acquire, will be to emulate Oliver Twist’s 
example and ask for more. It is quite impossible to 
summarise a report so crowded with curious informa- 
tion, witty comment, and historical insight, illumina- 
ting the whole development of the science of compara- 
tive anatomy. From the knowledge acquired as a 
collector of old ‘‘anatomies,’’ Dr. Cole has been able 
seventeenth and eighteenth centuries, which opened 
the way for those glaring instances of unscrupulous 
plagiarism that have ever been a source of amazement 
to us who live in such vastly different circum- 
stances. But no part of the discourse excels in 
piquancy and common sense the opening ‘apology ” 
for the study of the history of biology. 
A RECENT number of the Centralblatt fiir Bakterio- 
logie, Parasitenkunde, &c. (Zweite Abt., Band 38) 
contains a detailed account by O. Schneider-Orelli of 
investigations on the life-history and habits of Xyle- 
borus dispar, one of the bark-beetles (Scolytidz). 
This species, notorious for the injuries it inflicts on 
fruit-trees, is remarkable for its symbiosis with a 
fungus, Monilia candida, Hartig. The female beetles, 
fertilised in the autumn, hibernate in their burrows 
through the winter and swarm out in the following 
April and May. Each female then becomes the 
foundress of a new colony; she bores into a tree and 
makes a system of burrows, the walls of which be- 
come lined with a growth of the fungus, forming a 
dense white mass, the so-called “‘ambrosia.”” The 
mother-beetle lays her eggs in the burrows and the 
larvae feed on the ambrosia-fungus, not on the wood 
of the tree. Living cells or spores of the fungus are 
not to be found in the digestive tract of the larva, 
pupa, or newly hatched adult beetle, but the female 
beetles appear to take up the fungus from the walls 
of the burrow in which they have been bred, and the 
stomachs of the mother-beetles always contain a store 
of the fungus, capable of germinating. The culture 
is started in the new burrows by regurgitation of the 
fungus from the stomach, and is continued by the 
beetle plucking off clumps of the young culture and 
planting them further along in the burrow. If dis- 
turbed in her agricultural operations, the mother- 
zerozygous or wanting. He also dealt with the- 
to explain the loose methods of publication in the | 
