424 
NATURE 
[JUNE 17, 1915 

definition, and a number of statements are made 
which the reader must take on faith. In several 
instances the treatment is too sketchy to be of any 
practical value; thus two pages are allotted to 
photometry, half a page to thick lenses (in spite 
of their technical importance), five pages to radio- 
activity, and twenty-three to sound. Nevertheless, 
if these blemishes are allowed for, it may be 
granted that the book is clearly and interestingly 
written, well got up, and likely to excite and 
retain the interest of the reader; but to take full 
advantage of its good qualities the student must 
not come to it as a beginner. 
(4) Prof. Dessau’s book, the second volume of 
a large text-book of physics, is admirable in its 
elegance, clearness, and choice of matter. The 
chapters on thick lenses and optical instruments 
may especially be mentioned as models of concise- 
ness and lucidity. (Why is it that modern methods 
of determining refractive indices receive no men- 
tion in English books on physics other than those 
on physical chemistry?) But surely a book of 
600 pp. should have an index ! 

EVOLUTIONARY MEDICINE. 
(1) Evolution and Disease. By Dr. J. T. C. Nash. 
Pp. vili+73. (Bristol: John Wright and Sons, 
Ltd.; London: Simpkin, Marshall, Hamilton, 
Kent and Co., Ltd., 1915.) Price 3s. 6d. net. 
(2) The Vicious Circles of Neurasthenia and their 
Treatment. By Dr. J.B. Hurry. Pp. xv+go. 
(London: J. and A. Churchill, 1915.) Price 
Bss 6d. net: 
(1) ie this work Dr. Nash first traces the 
history of certain epidemic diseases, in 
particular the Black Death, during the Middle Ages 
in Great Britain. An interesting chapter deals 
with the medieval psychopathic epidemics, such 
as the dancing mania. Much of this has neces- 
sarily appeared elsewhere, but it is none the less 
convenient to have the scattered literature of the 
subject thus briefly epitomised. The reader will 
probably turn with most interest to the chapters 
dealing with evolution and disease—in particular 
with the evolution and mutations of disease germs. 
As regards diphtheria, for example, the author 
states that diphtheroid organisms in throat swabs 
are uncommon except in cases of definite sore 
throat or in “contacts” with diphtheria or sore 
throat, that genuine cases of diphtheria with 
typical diphtheria bacilli often show later only 
diphtheroid bacilli in the throat swabs, and that 
some streptococci, some torule, the Klebs-Léffler 
bacillus, Hofmann’s bacillus, and certain other 
diphtheroid bacilli, have a common ancestral 
origin, and concludes that the fact that bacteria 
and protozoa can be profoundly affected by en- 
NOL 12381,, VOL.395)| 


vironment is abundantly established, and evolutiom 
in relation to the germ cannot be gainsaid. 
A topical interest is introduced in the final chap- 
ter on war as a factor in the evolution of epi- 
demics. 
(2) Dr. Hurry describes with considerable skill 
the vicious circles associated with that protean 
disorder known as neurasthenia. As an instance 
of a “vicious circle,” that in connection with the 
heart may be quoted :— 
“The sequence of events is somewhat as fol- 
lows: The fear of organic heart disease leads to 
auto-suggested sensations in the cardiac region, 
followed by disturbance of the cardiac action, such 
as rapid heart, occasional extra beats with palpi- 
tation, and an intermittent pulse. The associated 
sensations then arouse distress and terror, which 
in their turn further disturb the cardiac action. 
Such attacks are especially common at night, 
and may be caused by nightmare, and the opera- 
tion of this Circle may reduce the neurasthenic 
person to a condition of utter misery. Even fatal 
syncope may result.” 
It will thus be seen that the neurasthenic condi- 
tion becomes evolved, as it were, given some 
factor which serves to start it and set in train the 
“vicious circle.” 
As regards treatment, while the principles are, 
it is true, indicated, the physician who desires real 
guidance will find little to help him, and we think 
that this part of the book might be usefully ex- 

tended. Io NG Ist, 
OUR BOOKSHELF, 
Heating and Ventilating Buildings. By Prof. 
R. C. Carpenter. Pp. xiv+598. Sixth Edi- 
tion. (New York: J. Wiley and Sons, Ince. ; 
London: Chapman and Jall, Ltd., 1915.) 
Price 15s. net. : 
Durinc the twenty years since this book was first 
published there have been many changes in 
methods of heating and ventilation. The present 
edition has been enlarged considerably by the 
addition of matter necessary to make it an 
up-to-date treatise on the subject. The author, 
who is well known as the professor of experi- 
mental engineering at the Cornell University, 
has dealt with the principles in a_ scientific 
manner, and has placed the various practical 
rules as far as possible on a rational foundation, 
at the same time avoiding the use of complicated 
mathematics. The earlier chapters are taken up 
with the properties of heat, the flow of water, 
steam and air, and the boilers and fittings 
required for steam and _ hot-water heaters. 
The remainder of the book contains thoroughly 
well illustrated descriptions of modern heating 
systems and includes gravity steam-heating, pump 
return steam-heating, hot-water and _ hot-air 
systems. There are also sections dealing with 
| mechanical ventilators, heating with electricity, 
