398 
NATURE 
[FEBRUARY 25, 1904 
perhaps absolutely essential, to life-development on the 
earth.”’ 
A close perusal of the subject-matter indicates, in 
the first place, two prominent facts. First, the 
masterly way in which Dr. Wallace has marshalled 
the available subject-matter to enforce his lines of 
argument, and second, the excessively clear and con- 
cise summary of the astronomical knowledge which 
he has employed. This latter is contained in the first 
six chapters, and although the author suggests that 
those who are fairly acquainted with modern astro- 
nomical literature might omit reading these, the 
account is so excellent that the advice should not be 
followed. 
It is not the object of this review to tell our readers 
whether Dr. Wallace is correct or not in the con- 
clusions at which he has arrived, for that would not 
be an easy matter, but to direct attention to a work 
which must be treated with considerable respect. 
Astronomical science has, during the last thirty years, 
made enormous strides, but the information that is 
needed when considering such a problem as is dealt 
with by Dr. Wallace is still very sparse, and is con- 
spicuously absent from many books which by their 
titles ought to contain it. 
Chapters vii. to ix. deal with the problems, Are the 
stars infinite in number? our relation to the Milky 
Way; and the uniformity of matter and its laws | 
In all of these the | 
throughout the stellar universe. 
author displays a very thorough acquaintance with the 
recent advances in these subjects. He concludes from 
such evidence that the stellar limited, 
that the solar system is nearly in a central position of 
the Milky Way, this position being probably a per- 
manent one, and, lastly, that the whole material 
universe is one as regards physical and chemical laws 
and material structure. 
In the next chapter he the essential 
characters of the living organism in a remarkably 
clear and definite manner, and points out the intimate 
connection between animal and vegetable life. 
The chapter which follows describes all the physical 
conditions essential for this organic life, and then the 
four subsequent ones point out how these conditions, 
in his opinion, exist only on one planet, our earth, in 
the solar system. Not only does he suggest that the 
earth alone is inhabited, but that the other planets of 
the system have never been and never will be the seat 
of organic life, since they never can produce the exact 
conditions that are considered necessary. 
The next and last chapter carries the argument into 
the starry realm beyond the solar system, and here 
the author gives his reasons for concluding that only a 
very few of these stars may be suns with life-support- 
ing planets. 
In considering man’s place in the universe it seems 
that the matter dealt with in chapter x., in which the 
author describes the essential characters of the living 
organism, contains the criterion on which the whole 
question of the habitability of other worlds turns. 
It is known that protoplasm is so complex chemically 
that it defies analysis, and protoplasm, to use Dr. 
Wallace’s words, ‘‘is, as it were, only the starting 
NO. 1791, VOL. 69] 
universe is 
sums up 
point or material out of which the infinitely varied 
structures of living beings are formed. The extreme 
mobility and changeability of the structure of these 
molecules enable the protoplasm to be continually 
modified both in constitution and form, and, by the 
substitution or addition of other elements, to serve 
special purposes.”’ 
May it not be that the very complex nature of proto- 
plasm and its very property, the ease with which it 
may be modified, enable it to adapt itself to the various 
conditions, such as distance from central orb, size, 
&c., that exist on the different planets at those epochs 
in their life’s history when the temperature conditions 
are within the prescribed limits ? 
Might not this element of living matter, working 
under somewhat different conditions, so affect the after 
products that they in their turn cotld weather the 
existing conditions, which to them would be natural 
and to us special ? 
To consider this earth as the only inhabited body 
in the stellar universe, a reversion -to prehistoric ideas, 
may or may not be an advance, but it will require very 
strong arguments before man can be brought to con- 
sider that his isolation in the cosmos is indeed a fact. 
The book, however, is one that should be read by 
all those interested in such a speculation, for specu- 
lation at the present time it can only be, and much 
valuable information may be learnt about the various 
subjects which the author has had to deal with in his 
broad survey. 
OUR BOOK SHELF. 
The Fauna of British India, including Ceylon and 
Burma. Published under the authority of the Secre- 
tary of State for India in Council. Edited by W. T. 
Blanford. Rhynchota. Vol. ii. Part. i. (Heterop- 
tera). By W. L. Distant. Pp. x+242. (London: 
Taylor and Francis, 1903.) Price ros. 
Mr. Distant is making good progress with the de- 
scription of the known species of Indian Rhynchota, 
and the editor informs us in his preface that the re- 
mainder of the volume will comprise all, or nearly all, 
the remaining families of the division Gymnocerata, 
thus leaving the bulk of the water-bugs for a third 
volume, which will complete the subject as far as the 
Heteroptera are concerned. The present instalment 
includes 371 species belonging to the families 
Lygeide, Pyrrhocoride, Tingidide, Phymatide, 
Arcedidze, Hebrida, Hydrometride, Henicocephalide, 
and the commencement of the Reduviide. The 
letterpress is executed in the same careful manner 
as in the first volume, and is illustrated by 167 excellent 
text illustrations. 
A considerable number of new species are described 
in the present part, and a very large proportion of the 
remainder have only become known to entomologists 
within the last few years, many of them, indeed, having 
been described by Mr. Distant, or others, as late as 
1903. When we consider that the Hemiptera have 
been far from exhaustively collected at present, and that 
many of the families include small plant-feeding 
species, it will be plain that a vast amount of work: still 
requires to be done before our knowledge of the Indian 
species can be considered as anything like complete. 
But such works as Mr. Distant’s cannot but give a vast 
impetus to the study, while those who know its extent 
will not be liable to repeat the amusing error of Lich- 
