162 
Analyses of Books. 
[March, 
Painting,” on the “ Origin of the Planetary System,” on 
“ Thought in Medicine,” and on “ Academic Freedom in German 
Universities.” Not many living men would venture to discourse 
before learned and critical audiences on so wide a range of topics, 
and no one probably would acquit himself so satisfactorily. But 
whilst we recognise the full value of the teachings of Prof. 
Helmholtz, we cannot but pronounce him a dangerous example 
for the student. The versatility which he exhibits is not shared 
by one mind in a million. 
Prof. Magnus may be regarded as having done for physics 
what Liebig did for chemistry. The modern physical laboratory 
arranged for experimental instruction in optics, heat, electricity, 
magnetism, is his creation. His collection of apparatus, which 
on his death he bequeathed to the University of Berlin, is a 
silent but emphatic testimony to his character. Every instru- 
ment is not merely the best procurable, but every requisite which 
may be wanted in the course of experimentation is sure to be 
close at hand. As a teacher he constantly urged upon his pupils 
the appeal to observation and experiment. He did not recognise 
the absolute distinction formerly admitted between the organic 
and the inorganic world, but, as Prof. Helmholtz says, “ in his 
research on the gases of the blood (1837) dealt a blow at the 
heart of vitalistic theories.” He is described as having led an 
especially happy life in the centre of an affectionate family, and 
in a circle of faithful and distinguished friends, whilst his cir- 
cumstances allowed him to devote his whole time to successful 
research. 
In the leCture on the relation of Optics to Painting we find 
mention of a remarkable faCt : the brightest colours of a painter 
are only about one hundred times as bright as his darkest shades. 
The brightest white on a picture when most brilliantly illuminated 
has probably one-twentieth of the brightness of white direCtly 
lighted up by the sun. On the other hand, white garments in 
moonlight or marble surfaces will always be from ten to twenty 
times as bright in a picture as in reality. 
In the concluding portion of the leCIure on the origin of the 
Planetary System, Prof. Helmholtz speculates on the possible 
extinction of organic life upon our earth. He seems to think it 
probable that animal forms may be developed capable of existing 
amidst the decreasing heat and light which must be expeCted in 
the remote future. He entertains the suggestion that meteoric 
stones may scatter germs of life in new worlds — a view which 
has involved him and Sir W. Thomson in a controversy with 
Prof. Zollner. But we do not see that this hypothesis serves 
in the least to explain the origin of life. We have still the alter- 
native, creation or spontaneous generation. If the latter is 
impossible in our world, why should it take place elsewhere ? 
As regards individual consciousness the author says — “ As yet 
we know of no faCt which can be established by scientific ob- 
