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August 13, 1885 | 
NATURE 
341 
school class for beginners. As it appears from his preface 
that this was the sole object of the author in writing the 
little book, he is entitled, we think, to consider that his 
object has been attained. 
Bacillary Phthists of the Lungs. 
translated by William H. Weddell. 
Paul, Trench and Co., 1885.) 
THIS is in many respects an unsatisfactory book. It is 
divided into seven parts. Of these the preliminaries and 
the first four parts comprise anatomical and histological 
notes, the biological study of micro-organisms generally, 
and the study of the bacillus tuberculosis especially, and 
all kinds of promiscuous notes on the causes of tubercu- 
losis ; but, owing to the dogmatic way in which these 
subjects are treated, the omission of details and the 
numerous mycological inaccuracies this portion of the 
book is very weak. The rest, treating of clinical, 
hygienic, and therapeutic subjects, is more within the 
author’s proper domain, and will be found instructive to 
the medical practitioner. 
Mineral Resources of the United States. By A. Williams. 
(Published by the U.S. Geological Survey, 1883.) 
THIS book consists of a series of essays, of various de- 
grees of importance, on the mining and metallurgic 
industries of the United States. The work has been 
mainly carried out by entrusting each subject, or a 
special branch of each subject, to a gentleman intimately 
acquainted with that branch. The thoroughness with 
which the subject is treated is shown by the fact that the 
natural history of so rare a substance as hiddenite is 
very fully discussed by the original discoverer, Mr. W. 
E. Hidden. 
Naturally the most important and the most extensive 
essays are those on coal, iron, copper, and zinc. Silver, 
the position of which is at present one of the most diffi- 
cult problems connected with the metals, was excluded 
by Act of Congress from the present investigation, and 
tables of the production of gold and silver in recent years 
are all the information given. Former publications of 
the U.S. Government have already made known the 
enormous wealth of the silver-mines, and have given fair 
means by which persons interested in mining may esti- 
mate the prospect of success in such undertakings. 
Under iron, an account is given of the Bower-Barff pro- 
cess of protecting iron from rust by means of a thin film of 
magnetic oxide—a process which bids fair, if it stand the 
trial of some years’ wear, to replace the process of 
galvanising. 
To professional people who need accurate information 
as to the condition of the various industries, the book 
possesses great value. It is also full of interest to the 
scientific mineralogist who has mainly to depend on the 
opening of new mines for fresh discoveries in the mineral 
kingdom. One cannot help regretting, however, the 
space given to a history of the divining-rod, ‘“ natural 
magnets,” and similar absurdities. The subject is as 
much out of place as an account of the astrological 
nonsense practised in the Middle Ages would be in a 
modern treatise on spherical astronomy. 
By Germain Sée, 
(London; Kegan 
LETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents. Neither can he undertake to return, 
or to correspond with the writers of, rejected manuscripts. 
No notice is taken of anonymous communications. 
[The Editor urgently requests correspondents to keep their letters 
as short as possible. The pressure on his space is so great 
that it is impossible otherwise to insure the appearance even 
of communications containing interesting and novel facts. | 
Pitcher Plants 
PERHAPS you will allow me to set ‘‘W. C. M.” right with 
egard to Sarracenia variolaris and pitcher plants generally 
(p. 295). Iam afraid the sources from whence he obtained his 
information were not very reliable, as will be seen from the 
following :-— 
There are six species of Sarracenia found in North America, 
all of them characterised by the same trumpet-shaped leaves 
growing in tufts, and in several of the species attaining a length 
ofa yard. In addition to these there is the Darlingtonia cali- 
fernica, which has long twisted trumpet-shaped leaves, the top 
of which is curved over, forming a sort of hood, and having a 
rather small aperture on each side. These constitute the whole 
of the pitcher plants of North America. ‘‘W. C. M.,” whilst 
professing to describe the ‘‘ curious characteristics” of the Sarra- 
cenia, really describes the leaf and pitcher of Nepenthes, which, 
as almost everybody knows, are tropical plants, mostly natives 
of the Indian Archipelago, and well known in this country as 
ornamental stove plants. The pitchers vary much in size, some 
of the species producing them quite eighteen inches long and 
capable of holding a quart of water, whilst others have pitchers 
no larger than a thimble. ‘‘ W. C. M.” is quite wrong in saying 
that the lids of the pitchers of Nepenthes, or indeed of any 
pitcher-plant known, close again after they have once opened. 
When the pitcher is about full-grown, the lid pushes open, 
widely in some species, only slightly in others, and remains 
quite stationary till the pitcher dies. When the lid opens, the 
pitcher is found to be about one-quarter filled with a sweetish 
watery liquid. Under cultivation it is necessary to keep the 
pitchers filled with water, or they soon shrivel ; and it is found 
that, however frequently the water is renewed, it soon acquires 
a slight sweetness ; so that the secretion of ‘‘ honey” going on 
in the pitcher must be somewhat copious. If the water which 
is in the pitcher when it first opens dries up, there is no further 
secretion of liquid—at least such is the case with cultivated 
plants. At Kew the oldest pitchers on the Nepenthes attract 
insects as long as they contain moisture. The Sarracenias have 
their pitchers formed by the folding and joining of the edges of 
the leaves, so as to make a long funnel which is wide at the 
mouth and narrowed to almost a point at the base. Over the 
mouth the flap-like lid is fixed and in some of the species 
stands erect so as to admit rain-water into the pitchers, whilst 
in others the lid curves over in such a manner as to hinder the 
rain from falling into them. In 1815 the then President of the 
Linnean Society, Dr. James McBride, read a communication 
on the fly-catching propensity of Sarracenias, from which the 
following is worth quoting, as it describes accurately what we 
have repeatedly observed in the collection of Sarracenias culti- 
vated at Kew. He says, writing chiefly about Savvacenta vario- 
aris: ‘*If, in the months of May, June, or July, when the 
leaves of these plants perform their extraordinary functions in 
the greatest perfection, some of them should be removed toa 
house and fixed in an erect position, it will soon be perceived 
that flies are attracted by them. These insects immediately 
approach the fauces of the leaves, and, leaning over their edges, 
appear to sip with eagerness something from their internal sur- 
face. In this position they linger, but, at length allured, as it 
would seem by the pleasures of taste, they enter the tubes. The 
fly, which has thus changed its situation, will be seen to stand 
unsteadily, it totters for a few seconds, slips, and falls to the 
bottom of the tube, where it is either drowned or attempts in 
yain to ascend against the points of the hairs. The fly seldom 
takes wing in its fall and escapes. In a house much infested 
with flies this entrapment goes on so rapidly that a tube is filled 
within a few hours, and it becomes necessary to add water, the 
natural quantity being insufficient to drown the imprisoned 
insects. The leaves of other species might well be employed as 
fly-catchers ; indeed I am credibly informed that they are in some 
neighbourhoods. The leaves of Sarracenia flava, although they are 
very capacious, and often grow to a height of three feet or 
more, are never found to contain so many insects as those 
of other species. The cause which attracts flies is evidently 
a sweet viscid substance resembling honey, secreted by, 
or exuding from, the internal surface of the tube. From 
the margin, where it commences, it does not extend lower than 
one-fourth of an inch. The falling of the insect as soon as it 
enters the tube is wholly attributable to the downward or in- 
verted position of the hairs of the internal surface of the leaf. 
At the bottom of a tube, split open, the hairs are plainly di- 
scernible pointing downwards ; as the eye ranges upwards they 
gradually become shorter and attenuated, till at, or just below, 
the surface covered by the bait, they are no longer perceptible 
to the naked eye nor to the most delicate touch. It is here that 
the fly cannot take a hold sufficiently strong to support itself, 
