302 TIIL CLASSICAL TRADITION 



Kowalevsky's classical memoir, Vcrsnch cincr natiirliclicn 

 Classification dcr fossilcn Hiiftliicrc, Osborn 1 writes : " This 

 work is a model union of the detailed study of form and 

 function with theory and the working hypothesis. It regards 

 the fossil not as a petrified skeleton, but as having belonged 

 to a moving and feeding animal ; every joint and facet has 

 a meaning, each cusp a certain significance. Rising to the 

 philosophy of the matter, it brings the mechanical perfection 

 and adaptiveness of different types into relation with environ- 

 ment, with changes of herbage, with the introduction of 

 grass. In this survey of competition it speculates upon -the 

 causes of the rise, spread, and extinction of each animal 

 group. In other words, the fossil quadrupeds are treated 

 biologically so far as is possible in the obscurity of the 

 past" (p. 8). The same high praise might with justice be 

 accorded to the work of Cope on the functional evolution 

 of the various types of limb-skeleton in Vertebrates, and on 

 the evolution of the teeth as well as to the work of other 

 American palaeontologists, including Osborn himself. 



Osborn's law of " adaptive radiation," which links on to 

 Darwin's law of divergence,- constitutes a brilliant vindication 

 of the functional point of view. " According to this law each 

 isolated region, if large and sufficiently varied in its topog- 

 raphy, soil, climate, and vegetation, will give rise to a 

 diversified mammalian fauna. From primitive central types 

 branches will spring off in all directions, with teeth and 

 prehensile organs modified to take advantage of every 

 possible opportunity of securing food, and in adaptation of 

 the body, limbs and feet to habitats of every kind, as shown 

 in the diagram [on p. 363]. The larger the region and the 

 more diverse the conditions, the greater the variety of 

 mammals which will result. 



" The most primitive mammals were probably small 

 insectivorous or omnivorous forms, theivforo with simple, 

 short-crowned teeth, of slow-moving, ambulatory, terrestrial, 

 or arboreal habit, and with short feet provided with claws. 

 In seeking food and avoiding enemies in different habitats 



1 The A^c of Mammals in Europe, Asia, and North America, Nc\v 

 York, K;IO. 



- Origin of Species, Oth cd., Chap. IV. 



