JANUARY 11, 1884.] 
very rocks forced him to the opinion that pro- 
pylite has no right whatever to be regarded as 
an independent rock-type, but is always an 
alteration product of diabase, diorite, or ande- 
site, by the change of the bisilicates to uralite 
or chlorite. 
In chapter iv. the author discusses theo- 
retically the structural results of faulting. He 
regards the schistose structure, so often ob- 
served in the andesite, as the result of faulting 
under intense lateral pressure, and shows that 
such sheets would naturally tend to arrange 
themselves in a logarithmic curve, as seems to 
be the case at the Comstock. 
The chapter on chemistry is not very satis- 
factory. But few new rock analyses are offered, 
and none are ably discussed in connection with 
the microscopic diagnosis. The finding of very 
small quantities of ore in the accompanying 
rocks, especially the diabase, would seem to 
suggest just the reverse course of reasoning 
from that adopted ; and certainly none of the 
facts presented appear to warrant the sup- 
planting of von Richthofen’s theory, that the 
ores came from great depths, by one ascribing 
their deposit to segregation produced by ordi- 
nary solvents (hydrogen sulphide and carbon 
dioxide) from the rocks at the side of the lode. 
The discussion of the heat-phenomena of 
the lode receives especial attention in chapter 
vii. The rapid increase of temperature is well 
known to be one of the great hinderances in 
working the mines, being nearly double the 
average observed elsewhere. This has been 
accounted for by some by chemical action: 
as, for instance, the oxidation of pyrite, or 
the kaolinization of felspar. The author con- 
cludes, however, in light of the careful experi- 
ments conducted by Dr. Barus in reference to 
the latter theory, that such an explanation is 
untenable; and that the source of the heat 
must be sought in former, and not entirely 
extinct, volcanic activity. 
The observations of Dr. Barus, bearing on 
the electrical activity of ore-bodies, are re- 
corded in chapter x. They relate as well to 
the deposits at Eureka as to those in the Com- 
stock, and, while not directly productive of 
results of practical importance to the pro- 
spector or miner, possess a very considerable 
scientific interest. 
The execution of the plates and maps is up 
to the usual high standard of the survey pub- 
lications. The chromolithographic representa- 
tions of rock-sections in polarized light are 
particularly successful, and, as far as,my expe- 
rience reaches, are the best of the kind yet 
produced anywhere. 
SCIENCE. 
49 
MARTIN'S ELEMENTARY PHYSIOLOGY. 
The human body: an elementary text-book of anatomy, 
physiology, and hygiene. By H. NewEeLt Mapr- 
TIN. New York, Holt, 1883. 11+355 p., 4 pl., 
ikastr. * 16°. 
Tus volume forms the second volume in 
the ‘ American scientific series, Briefer course,’ 
published by the Messrs. Holt. It is an 
abridgment of a larger work by the same 
author, and is intended for use in schools and 
academies. The demand for such a book, 
and the difficulty of preparing one, are well 
known to any one who has sought in vain, 
among the numerous text-books now in the 
market, for one really scientific, and suited to 
the age and needs of his pupils. It is a book 
of about three hundred and fifty pages, but 
how it could well have been made smaller we 
do not see. The language is simple, the style 
clear, and the book, at the same time, easily 
comprehensible and thoroughly scientific. It 
is elementary without being superficial. The 
essential facts are pointed out to the pupil 
without taxing his memory with a mass of 
unimportant details, or vexing him with con- 
flicting theories on unsettled questions. At the 
end of each chapter these are condensed, and 
their connection shown in a brief summary, 
which aids the memory, and excites the interest 
of the pupil. From the physiological facts are 
deduced the most important laws of hygiene, 
while the student gains glimpses of wider fields 
of anatomy and zoology in the footnotes. 
A new and most important characteristic of 
the work is the series of directions to teachers 
for demonstrating on frogs and rats the main 
outlines of anatomy, and for physiological ex- 
periments accompanying each chapter. These 
are all clearly explained, and easy, yet it is 
to be feared that they will be neglected by 
three-fourths of the teachers using the book. 
Their importance might well and justly have 
been far more strongly urged in the preface. 
We hear every year less of the objections to 
such dissections. The great difficulty is, that 
most of the teachers in our schools and acade- 
mies have been taught physiology in the old 
way; and many of them have never even seen 
the inside of a frog. They greatly over-esti- 
mate the difficulties of such dissections and 
experiments, and do not appreciate that the 
sight of the real organ or process is worth 
more to the pupil than an hour’s study of text- 
books or charts. If the teacher will once try 
fairly the experiment of following these direc- 
tions, he will be surprised at the small amount 
of extra work caused, and at the enthusiasm 
