76 Notices of Scientific Works. [Jan., 



a consideration of the laws -which govern the material world, and a 

 comparison of them with what we know of those which prevail in 

 the domain of organic life. With great acuteness and force of illus- 

 tration, Mr. Murphy points out that while it is a feasible hypothesis 

 that many of the structures which we see in the animal and vege- 

 table worlds are attributable to Natural Selection, or " the Survival 

 of the Fittest," acting through a long course of generations, there 

 are others which it is impossible to conceive can have become 

 developed through the operation of this law, or of that promulgated 

 by Herbert Spencer, depending on the mechanical adaptation of 

 structure to function by the force of external agency. To this cate- 

 gory belong such organisms in the vegetable kingdom as the hard, 

 woody shell that protects the nut, but still more conspicuously all 

 the most complex organs of the higher orders of animals. "We will 

 give the argument in Mr. Murphy's own words : — 



" There are structures for the origin of which it is, I believe, 

 utterly impossible to account by any merely physical theory. I 

 refer to such organs as the eye and the ear. If it is certain, as I 

 think it is, that the flow of the nutritive fluids through cellular 

 tissue, for successive generations, must have a tendency to form a 

 rudimentary circulating apparatus, it is at least equally obvious that 

 the action of light falling on the eye for any number of genera- 

 tions, can have no similar tendency to produce the optical apparatus 

 of the eye. Nor can the constant exercise of the eye in the act of 

 seeing have any such effect. The exercise of the eye, within the 

 limits of what is healthful, does, no doubt, tend to increase the sen- 

 sitiveness of the retina ; and I do not say it is impossible, though I 

 do not admit it as probable, that the muscular arrangements to 

 which the mobility of the eyeballs and eyelids is due, may have been 

 produced by the effort to move them, continued through successive 

 generations ; and that the expansion of nerves over the retina may 

 have been produced by the constant stimulation of the nerves them- 

 selves. But no such merely physical theory will account for the 

 origin of the special complexities of the visual apparatus Neither 

 the action of light on the eye, nor the actions of the eye itself, can 

 have the slightest tendency to produce the wondrously complex his- 

 tological structure of the retina ; nor to form the transparent 

 humours of the eye into lenses; nor to produce the deposit of black 

 pigment that absorbs the stray rays which would otherwise hinder 

 clear vision ; nor to produce the iris, and endow it with the power 

 of partly closing under a strong light so as to protect the retina, 

 and expanding again when the light is withdrawn ; nor to give the 

 iris its two nervous convexions, of which one has its root in the 

 sympathetic ganglia, and causes expansion, while the other has its 

 root in the brain, and causes contraction." 



Admitting, then, as Mr. Murphy does, the premiss of the 



