775 
i8 80.] Working v. Fighting . 
depend upon light only through the mediation of the eyes.” 
With all due deference I must beg to point out that accord- 
ing to the researches of Moleschott and F ubini (Mitheilungen aus 
deni Embry ologischen Institut zu I Vicn y iv., p. 265) the action 
of light in promoting the metamorphosis of matter is exerted 
not merely through the eyes but through the skin, and can 
be traced even in blind frogs, birds, and mammals. If the 
eye alone or the skin alone is stimulated by light, the in- 
creased escape of carbonic acid is smaller than when the 
entire body is exposed to light. 
With reference to the brilliant colouration of the sea- 
anemones and the true coral-polypes often compared to 
submarine flowers, Prof. Semper shows that this beauty is 
not to be explained on the principle of sexual selection. 
Both males and females being rooted fast cannot seek each 
other, but emit their sexual secretions into the water, leaving 
it to the currents to effect the fertilisation of the ova. As 
little can the decoration of these polypes be classed among 
the “ protective ” or the “ warning ” colours. They 
are not concealed but rendered more conspicuous, both 
to their possible prey and to their enemies, and the latter, 
such as the Scaridcz and the Diodontidce , are not in the least 
deterred by the sight. We must, therefore, refer these 
colours to the “ typical ” class described by Mr. Wallace * 
Prof. Semper is, however, inclined to hope that both the 
production of pigments and their distribution in different parts 
of the animal system may be soon rendered intelligible. He 
admits the existence of mimicry, as established by Bates and 
Wallace, and detects instances of it even among snails. But 
he adds the caution that any agency which may, indeed, seleCt, 
but is unable to transform, cannot be regarded as the efficient 
cause of any phenomenon. This warning, which the author 
reiterates, marks his distinction from that of not a few natu- 
ralists who have dealt with the question of Evolution. But 
the same lesson is to be found, though perhaps less explicitly, 
in the work of Mr. Wallace. He, too, urges that geographical 
and geological changes, “ the alternations of warm and cold, 
or of uniform and excessive climates of almost perpetual 
spring in arCtic as well as in temperate lands, with occasional 
phases of cold culminating at remote intervals in glacial 
epochs ” have played not a mere selecting but a modifying 
part and have thus produced “ some of the more remarkable 
changes in the specific character of organisms.” Hence it 
is plain that the co-discoverer of “ natural selection ” guards 
* Macmillan’s Magazine, Sept., 1877, p. 392- 
