18 HISTORICAL SKETCH 



other passages scattered through M. Lecoq's large work, 

 make it a little doubtful how far he extends his views on the 

 modification of species. 



The 'Philosophy of Creation' has been treated in a mas- 

 terly manner by the Rev. Baden Powell, in his 'Essays on the 

 Unity of Worlds,' 1855. Nothing can be more striking than 

 the manner in which he shows that the introduction of new 

 species is "a regular, not a casual phenomenon," or, as Sir 

 John Herschel expresses it, "a natural in contradistinction to 

 a miraculous process." 



The third volume of the 'Journal of the Linnean Society' 

 contains papers, read July ist, 1858, by Mr. Wallace and my- 

 self, in which, as stated in the introductory remarks to this 

 volume, the theory of Natural Selection is promulgated by 

 Mr. Wallace with admirable force and clearness. 



Von Baer, towards whom all zoologists feel so profound a 

 respect, expressed about the year 1859 (see Prof. Rudolph 

 Wagner, 'Zoologisch-Anthropologische Untersuchungen,* 

 1861, s. 51) his conviction, chiefly grounded on the laws of 

 geographical distribution, that forms now perfectly distinct 

 have descended from a single parent-form. 



In June, 1859, Professor Huxley gave a lecture before the 

 Royal Institution on the 'Persistent Types of Animal Life.' 

 Referring to such cases, he remarks, "It is diflicult to com- 

 prehend the meaning of such facts as these, if we suppose 

 that each species of animal and plant, or each great type of 

 organisation, was formed and placed upon the surface of the 

 globe at long intervals by a distinct act of creative power; 

 and it is well to recollect that such an assumption is as un- 

 supported by tradition or revelation as it is opposed to the 

 general analogy of nature. If, on the other hand, we view 

 'Persistent Types' in relation to that hypothesis which sup- 

 poses the species living at any time to be the result of the 

 gradual modification of pre-existing species a hypothesis 

 v/hicli, though unproven, and sadly damaged by some of it.s 

 supporters, is yet the only one to which physiology lends any 

 countenance; their existence would seem to show that the 

 amount of modification which living beings have undergone 

 during geological time is but very small in relation to the 

 whole series of changes which they have sufifered." 



