410 THE INDUCTIONS OF BIOLOGY. • 



the forms resulting from such far greater deviations, heing 

 regarded as typically distinct forms, will not be taken as 

 evidence of great change in an original type. That which 

 Prof. Huxley's argument proves, and that only which he 

 considers it to prove, is that organisms have no innate 

 tendencies to assume higher forms ; and that " any admissible 

 hypothesis of progressive modification, must be compatible 

 with persistence without progression through indefinite 

 periods." 



One very significant fact must be added concerning the 

 relation between distribution in Time and distribution in 

 Space. I quote it from Mr. Darwin : — " Mr. Clift many years 

 ago showed that the fossil mammals from the Australian 

 caves were closely allied to the living marsupials of that con- 

 tinent. In South America a similar relationship is manifest, 

 even to an uneducated e3^e, in the gigantic pieces of armour 

 like those of the armadillo, found in several parts of La Plata ; 

 and Professor Owen has shown in the most striking manner 

 that most of the fossil mammals, buried there in such num- 

 bers, are related to the South American types. This relation- 

 ship is even more clearly seen in the wonderland collection of 

 fossil bones made by MM. Lund and Clausen in the caves of 

 Brazil. I was so much impressed with these facts that I 

 strongly insisted, in 1839 and 1845, on this ^ law of the suc- 

 cession of types,' — on ^this wonderful relationship in the 

 same continent between the dead and the living.' Professor 

 Owen has subsequently extended the same generalization to 

 the Mammals of the Old World. We see the same law in 

 this author's restorations of the extinct and gigantic birds of 

 New Zealand. We see it also in the birds of the caves of 

 Brazil. Mr. Woodward has shown that the same law holds 

 good with sea-shells, but from the wide distribution of most 

 genera of molluscs, it is not well displayed by them. Other 

 cases could be added, as the relation between the extinct 

 and living landshells of Madeira, and between the extinct 

 and living brackish-water shells of the Aralo- Caspian Sea/' 



