HISTORICAL SKETCH. 



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 ' con- 

 tains papers, read July 1st, 1858, by Mr. Wallace and myself, 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. Eudolph Wagner, ' Zoolo- 

 gisch-Anthropologische TJntersuchungen,' 1861, s. 51) his convic- 

 tion, 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 Iloyal 

 Institution on the ' Persistent Types of Animal life.' Referring to 

 such cases, he remarks, " It is difficult to comprehend 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 unsupported 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 

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

 gradual modification of pre-existing species — a hypothesis which, 

 though unproven, and sadly damaged by some of its 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 undergoue during geological time is but 

 veiy small in relation to the whole series of changes which they 

 have suffered." 



In December, 1859, Dr. Hooker published his { Introduction to 

 the Australian Flora.' In the first part of this great work he admits 

 the truth, of the descent and modification of species, and supports 

 this doctrine by many original observations. 



The first edition of this work was published on November 2-1 th ; 

 1859, and the second edition on Januar}' 7th, I860. 



