226 LAY SERMONS, ESSAYS, AND REVIEWS. [xii. 



to be, we confidently appeal to all practical naturalists, whether 

 zoologists, botanists, or palaeontologists, to say if, in the vast 

 majority of cases, they know, or mean to affirm, anything more 

 of the group of animals or plants they so denominate than what 

 has just been stated. Even the most decided advocates of the 

 received doctrines respecting species admit this. 



&quot;I apprehend,&quot; says Professor Owen, 1 &quot;that few naturalists now 

 adays, in describing and proposing a name for what they call *a new 

 species, use that term to signify what was meant by it twenty or thirty 

 years ago ; that is, an originally distinct creation, maintaining its primitive 

 distinction by obstructive generative peculiarities. The proposer of the 

 new species now intends to state no more than he actually knows ; as, for 

 example, that the differences on which he founds the specific character are 

 constant in individuals of both sexes, so far as observation has reached ; 

 and that they are not due to domestication or to artificially superinduced 

 external circumstances, or to any outward influence within his cognizance ; 

 that the species is wild, or is such as it appears by Nature.&quot; 



If we consider, in fact, that by far the largest proportion of 

 recorded existing species are known only by the study of their 

 skins, or bones, or other lifeless exuvia ; that we are acquainted 

 with none, or next to none, of their physiological peculiarities, 

 beyond those which can be deduced from their structure, or are 

 open to cursory observation ; and that we cannot hope to learn 

 more of any of those extinct forms of life which now constitute 

 no inconsiderable proportion of the known Flora and Fauna of 

 the world : it is obvious that the definitions of these species can 

 be only of a purely structural or morphological character. It is 

 probable that naturalists would have avoided much confusion of 

 ideas if they had more frequently borne the necessary limitations 

 of our knowledge in mind. But while it may safely be admitted 

 that we are acquainted with only the morphological characters 

 of the vast majority of species the functional, or physiological, 

 peculiarities of a few have been carefully investigated, and the 

 result of that study forms a large and most interesting portion of 

 the physiology of reproduction. 



The student of Nature wonders the more and is astonished the 



1 On the Osteology of the Chimpanzees and Orangs : Transactions of the 

 Zoological Society, 1858. 



