3i8 



NATURE 



\^Fcb. 22, 1872 



3. Between the dates of these two cold waves there are 

 located, according to all the cycles observed, even in- 

 cluding that earlier one otherwise exceptional, three 

 moderate and nearly equidistant heat-waves, with their 

 two intervening and very moderate cold waves, but their 

 characters are quite unimportant as compared with what 

 is alluded to under heads i and 2 ; and with regard to all 

 the waves, it may be just to state that there has been in 

 observation more uniformity, and will be therefore in pre- 

 diction more certainty for their dates than for their 

 intensities. C. PiAZZi Smyth 



February 1873 



DARWIN'S ORIGIN OF SPECIES 



The Origin of Species by means of Natural Selection; or 

 the Preservation of Favoured Races in the Struggle 

 for Life. By Charles Darwin, M.A., F.R.S. Sixth 

 edition, with additions and corrections. (London : J. 



Murray, 1872.) 



FEW are the writers, scientific or otherwise, who ca 

 afford, in every successive edition of their works, t° 

 place side by side the passages which they have seen rea- 

 son to alter, from a change of view or any other cause. 

 And yet to this point we find especial attention called in 

 each succeeding edition of Mr. Darwin's " Origin of 

 Species." And herein lies the true humility of the man 

 of science. Science is often charged with being arrogant. 

 But the true student of Nature cannot be otherwise than 

 humble-minded. That man is unworthy of the name of 

 a man of science who, whatever may be his special branch 

 of study, has not materially altered his views on some 

 important points within the last twelve years.* The 

 means at our command for obtaining correct views of 

 the laws which govern Nature are ever increasing, and 

 if we only 



Let knowledge grow from move to more, 

 this can but cause that * 



More of reverence in us dwell, 

 reverence for the eternal constancy of Nature's laws, with 

 respect to which we even yet know so little. But a false 

 pride more often tempts men to conceal than to avow their 

 changeof opinion. Mr. Darwincarries the contrary practice 

 perhaps to an excess. But such a course necessarily dis- 

 arms criticism of its sting ; and if the learner sometimes 

 ventures to point out wherein he differs from the master's 

 conclusions, it is only in the hope that the interchange of 

 opinion may lead to a removal of the difficulties which 

 prevent a complete accord of thought. 



The sixth edition of the " Origin of Species " is con- 

 siderably smaller than its predecessors ; but this does 

 not arise from any diminution of matter, but from the 

 use of smaller type. There has been, in fact, considerable 

 addition, and our province will be simply to call attention 

 to those points in which previous editions have been 

 amended or amplified. Already, in the fifth edition, Mr. 

 Darwin had stated that the able criticism of his work 

 which appeared in the North British Rcviciu hp.d induced 

 him to modify his views with regard to the frequency of 

 the occurrence of characters which are not useful to the 



'rlie first edilion of the "Origin of Species" 



; published in 1S59. 



individual ; we find now, on some other points, a similar 

 modification of opinion. 



It has always seemed to us that one of the weakest 

 parts of Mr. Darwin's statement of the theory of natural 

 selection is the emphasis with which he asserts that single 

 instances of departure from the law would prove the 

 theory to be unsound. In the present edition, speaking 

 of the rattle of the rattlesnake^the only effect of which 

 has been stated to be to direct to the snake the attention 

 of its enemies — he goes out of the way to repeat that 

 "if it could be proved that any part of the structure 

 of any one species had been formed for the exclusive 

 good of another species, it would annihilate his 

 theory." Why it would annihilate his theory, we 

 must confess we are unable to understand ; since Mr. 

 Darwin repeats in this edition even more emphatically 

 than in previous ones that " he is convinced that natural 

 selection has been the main, but not the exclusive, means 

 of modification of species." Since then other causes have 

 been at work to cause the evolution of species, why may 

 not some of these causes be able to produce parts bene- 

 ficial to the race rather than to the species? In the 

 special case, however, under consideration, the rattle of 

 the rattlesnake, an American naturahst comes to the 

 rescue of the Darwinian theory. Mr. Darwin was 

 probably not aware at the time of writing that Prof. 

 Shaler had stated his belief, from the result of observation, 

 that the rattlesnake's rattle is actually beneficial to it, its 

 object being to imitate the sound of the cicada or other 

 insect which forms the food of many birds, thus attracting 

 them within its power, and accounting for the apparent 

 " fascination " of its prey, which must now be consigned 

 to the limbo of travellers' tales. 



The greater part of the additional matter in this edition 

 is naturally devoted to a I'eply to the objections urged in 

 Mr. Mivart's " Genesis of Species." In replying to Mr. 

 Mivart's objection to the theory that "mimicry" has re- 

 sulted by the process of natural selection, on the ground 

 that the early stages of resemblance would have no useful 

 tendency, the following sentences appear to us to be open 

 to objection, or to be wanting in clearness : — " But in all 

 the foregoing cases the insects, in their original state, no 

 doubt pi'esented some rude and accidental resemblance 

 to an object commonly found in the stations frequented 

 by them." " Assuming that an insect originally happened 

 to resemble in some degree a dead twig or a decayed leaf" 

 What is meant by the "original state" of an insect ? Every 

 insect-form must have been evolved from some previously 

 existing simpler form by a gradual process, and the " rude 

 or accidental resemblance" must be due to the operation 

 of the same causes that produced the finished likeness. 

 We must acknowledge that Mr. Darwin appears to 

 us to fail to grapple with the difficulty in the way of 

 the application of his theory, that cither the early 

 stages of the " mimicry " are useless, or that the 

 exact reproduction of figure and pattern in the " mimic- 

 ing" insect is a mere freak of .nature. Mr. Darwin 

 states his belief that " the sight of birds is probably 

 sharper than ours," which would tell heavily against the 

 utility of the first approaches towards resemblance ; Mr. 

 Wallace, if we recollect rightly, has expressed a contrary 

 opinion. 



Mr. Mivart's objection with regard to the curious fact 



