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[ApRIL 28, 1904 
suddenly alter its habits when placed on another host 
B to which it is not yet attuned, and consequently fails 
to infect B. But, as Marshall Ward showed, the host 
B may be merely a closely related variety of A, whence 
we must infer that the differences of food-material and 
so forth may be very small, and it is not surprising 
that occasionally a spore from A may succeed in in- 
fecting B, possibly when the latter is ‘‘ off its guard,” 
as it were, and short of its supplies of resistant 
materials or unduly lavish of its stores of attractive 
substances, or possibly because the spore in question 
happens to be better equipped than usual with the 
necessary solvents or poisons needed to break down the 
normal resistance of B. Be this as it may, once the 
fungus of A has gained a hold on B, it can now go 
on infecting B by means of its spores—it has now 
adapted itself to B. 
But Marshall Ward showed that, while the fungus 
on A may fail to infect B, it may be readily able to 
infect a third related variety of host-plant C, and after 
adapting itself to C it may then pass easily to B; thus 
C becomes a bridging form from A to B. 
Klebahn in sections xiv. and xv. discusses these 
matters, and the gradations of specific variation and 
their bearing on the theory of descent at great length, 
and concludes, 
‘The manifold characters of the existing biological 
species and races appear to have come into being owing 
to the alternating extensions and restrictions of the 
area of nutritive plants. These changes, and especially 
the restrictions of area, have been influenced by adapt- 
ation and selection, but many observations indicate 
that internal developmental tendencies, as yet entirely 
unexplained, have also played a part in determining 
the direction of the evolution.”’ 
Not much is gained by the latter phrase, but it at 
least shows the lines along which the thoughts of 
modern pathologists are tending. 
Section xvi. deals with the question of the origin of 
hetercecism. Klebahn appears to doubt whether the 
increase of virulence said to be exhibited by A®cidium 
spores from barberry, as contrasted with uredo-spores 
grown on the wheat itself, can be maintained, and in- 
clines to the belief that an advantageous utilisation of 
the periodic phenomena of vegetation is the 
key to the problem. 
The author then proceeds to the discussion of pre- 
disposition, and accepts Marshall Ward’s researches 
showing that anatomical peculiarities on the part of 
the host-plant do not explain it, concluding that in part 
chemical constitution, in part forces or factors of un- 
known nature in the protoplasm, are at the bottom 
rather 
of the question. 
The concluding section of this part concerns the 
spermogonia, and views as to the alleged sexuality of 
the rust-fungi. The maintained that the 
spermatia are now functionless, and the author doubts 
the sexual character ascribed by Sappin-Trouffy and 
Dangeard to certain nuclear fusions in the development 
of teleutospores. 
view is 
Part ii. is essentially a work of reference for investi- 
gators, and deals very thoroughly with all the special 
points. in the biology of the various species of 
hetercecious Uredinez raised by the Tulasnes, De Bary, 
NO. 1800, VOL. 69 | 
Dietel, Fischer, Magnus, Eriksson and Henning, 
Marshall Ward and other workers, including—by no 
means the least important—the author himself. 
A very complete account is given of Eriksson’s work 
on the rusts of the cereals, and of that of Marshall 
Ward on the brome rusts, and it is probably not too 
much to say that a more thorough and masterly work 
on the subject has never yet been produced. 
That Klebahn’s work will have a wide influence in 
furthering investigation into these extraordinary and 
important parasites cannot be doubted. 
A STUDY OF RABIES. 
Rabies: its Place among Germ-diseases and its Origin 
in the Animal Kingdom. By David Sime, M.D. 
Pp. xii+290. (Cambridge: University Press, 1903.)) 
Price ros. 6d. net. 
HE admiration with which we must regaré 
Pasteur’s studies on rabies is increased by the 
fact that the actual microbe which causes the disease 
is unknown. Pasteur, nevertheless, by a_ logical! 
application of the facts known concerning other patho- 
genic microbes, triumphed over this difficulty, and pre- 
sented the world with a method of preventive inocula- 
tion against hydrophobia. He owed this achievement | 
to the rigid and laborious series of experiments with 
which he was scrupulously careful to control his 
theories. 
It is strange that Dr. Sime, with this example con- 
stantly before his eyes, should have been absolutely 
blind to its lesson. Anyone who seriously proposes to 
add to our knowledge of rabies must follow Pasteur’s 
methods. No advance is likely to be made by the most 
ingenious reasoning unsupported by practical demon- 
stration; we have no use at all nowadays for armchair | 
pathology. Dr. Sime’s work is beautifully printed 
and written in excellent English; it bears evidence of 
very wide reading and of careful though fanci‘ul 
thought. But it is wordy to an exasperating degree, 
and the perpetual use of inverted commas and italics 
becomes almost a nightmare. There is no evidence 
from first to last that the writer has attempted to 
substantiate any one of the remarkable views which 
he sets forth by a single practical experiment. 
There is room in the English language for a good 
monograph on rabies, but instead of giving a plain 
and straightforward account of what is at present 
known about the disease, which it is probable that 
Dr. Sime would have been competent to do, he presents 
us with a ‘‘ study ”’ of rabies from a number of theo- 
retical standpoints, at times embroidered with ex- 
cursions into transcendental bacteriology. It must 
suffice here to give a few examples only of the strange 
views supported by the author. The discussion as to 
the order of germ-diseases to which rabies belongs 
is based on a classification with which we are un- 
familiar. Dr. Sime sharply divides infective diseases 
into two groups—those which protect against future 
attacks and those which do not; for these he employs 
the singularly unhappy names ‘“‘ prophylactic’? and 
‘* preventive ’’ respectively. Why a disease which 
does not protect should be called ‘* preventive ’’ is not 
