582 M0EPH0L0C4ICAL METHOD AND RECENT PROGRESS IN ZOOLOGY. 



Those ol" us who have li\'c'd and worked throu^^hout this memorable 

 period have had a unique experience, for never has there been prog- 

 ress SO rapid, accumuhition of observations so extensive and exact. 

 Of the 386,000 living- animal species, to compute the estimate low, 

 every one available has been lain under hand, with the result that our 

 annual literarv output now amounts to close upon lO.OOO contri})utions, 

 the description of new genera and sul)g'enera, say l.TOt). ^Nlore than 

 one-half of this vast series refer to the Insecta alone; l)ut notwith- 

 standing- this, the I'ecords of facts of structure and development, with 

 which most of us are concerned, now amount to a formidable mass, 

 calculated to awe the unlettered looker-on, to overwhelm the earnest 

 devotee, unless by specializing- he can s(H'ure relief. As an example 

 of what may occur, it ma}^ be remarked that a recent exploration of 

 the g-reat African lakes has resulted in the discovery of over 130 new 

 species. 



As to the nature of this imprecedented progress, it will suffice to 

 consider the Earthworms. In 1874 few were known to us. An ad- 

 vance in our knowledg-e, which had then comiuenced. had made known 

 but few more which seemed likely to ^^ield result. Darwin's book 

 upon them liad not appeared. -Some were exotic, it is true, but no 

 one susj)ected that a group so restricted in their ha])its could reveal 

 aught beyond a dull monotony of form and structure. Never was 

 surmise more wide of the mark, for the coml)ined investigations of a 

 score of earnest workers in all parts of the world have in the interval 

 recorded some Too odd species of al)out 110 genera. Mainly exotic, 

 they exhibit among themselves a structural variation of the widest 

 possible range. Not only do we recognize littoral and l)ranchiate 

 forms, ))ut others acluetous and leech-like in ha))it. to the extent of 

 the discovery of a morphological overlap with the leeches, under 

 which we are now compelled to remo\e them from their old associa- 

 tion with the flat worms, and to luiite them with the earthworms. 

 And we even lind these animals, as represented by the AeantJiodriUdm^ 

 coming prominently into considerations which involve the theory of a 

 former antarctic continent, one of the most revolutionary zoo-geogra- 

 phical topics of our time. 



This case of th(> earthworm may be taken as typical of the rest, since 

 for each and evei-y class and order of animal forms the progress of the 

 period through which w(> have })assed since last we assembled luM-e has 

 produccnl revolutionary results. Our knowledge of facts has become 

 materially enhanced; our classifications, at best but the woi'king ex- 

 pression of our ideas, have be(Mi to a large extent replaced in clearer, 

 more couiprehensive, schemes; and we are to-day ena])l(Hl to deduce, 

 with an accuracy proportionate to our increasinl knowledge of fact, 

 the nature of the interrelationships of the living forms which with 

 ourselvc\s iniiabit the (\'U-th. 



