ii2 Analyses of Books. [February, 
human immortality is denied by modern psychologists, we can- 
not help thinking that the demonstration of a continued existence 
of the individual after the phenomenon known as death would 
be the most splendid service which could be rendered to 
Science. 
Those of our readers who wish for a further acquaintance 
with this little work, abounding as it does in matter worthy of 
the most serious study, will do well to re-peruse the author’s two 
memoirs in the “ Journal of Science ” above referred to. 
The Natural Conditions of Existence as they affect Animal Life. 
By Karl Semper, Professor of (? at) the University of 
Wurzburg. London : C. Kegan Paul and Co. 
The original German edition of this interesting work has been 
made the subjeCt of an article in our December number for last 
year. Hence we can say but little on the version now before us. 
The translator supplies a valuable note showing that, contrary 
to Prof. Semper’s opinion, carbonic acid has been actually de- 
composed by green-coloured animals. But we dissent here from 
the author’s reasoning ; if a substance presents the elementary 
composition of chlorophyll, and displays the same chemical re- 
actions and speCtroscopic characters, we do not see that its 
ability or inability to decompose chlorophyll under the influence 
of sunlight is an essential question. That it possesses this pro- 
perty when forming part of the living vegetable tissue is scarcely 
a sufficient proof that the same result must be produced under 
very different circumstances. That chlorophyll aCts as an organ 
in plants does not warrant us in concluding that its functions, if 
present in animals, must be the same. 
As regards Mr. Buxton’s interesting experiment of allowing 
tropical cockatoos to live in the open air in England, we must 
remark that the winter of 1867-68 was unusually mild, the 
greatest cold recorded by a thermometer fixed in the wood being 
only about 29 0 F. Such experiments, owing to the bird-mur- 
dering propensities of the British public, can only be attempted 
by the proprietors of extensive domains, and we share Prof. 
Semper’s regret that on Mr. Buxton’s death the observations 
were brought to an end. The faCts already noticed warrant at 
least a supicion that many of the more splendid forms of animal 
life may have been extirpated in higher latitudes not so much by 
the direCt aCtion of cold as by the difficulty of finding, during 
the winter season, food and shelter from enemies. 
In a note the author, referring to the question whether similar 
organic forms can be derived from independent parent-stocks, 
