GROWTH. Ill 



considerable height, the majority are but of humble growth. 

 The Endogens, including at one extreme small grasses and 

 at the other tall palms, show us an average and a maximum 

 greater than that reached by the Acrogens. And the En 

 dogens are exceeded by the Exogens ; among which are 

 found the monarchs of the vegetal kingdom. Pass 



ing to animals, we meet the fact that the size attained by 

 Vertebrata is usually much greater than the size attained by 

 Invertebrata. Of invertebrate animals the smallest, classed 

 as Protozoa, are also the simplest; and the largest, be 

 longing to the Annulosa and Mollusca, are among the most 

 complex of their respective types. Of vertebrate animals 

 we see that the greatest are Mammals ; and that though, 

 in past epochs, there were reptiles of vast bulk, their bulk 

 did not equal that of the whale. Between reptiles and 

 birds, and between land -vertebrates and aquatic vertebrates, 

 the relation does not hold : the conditions of existence be 

 ing in these cases widely different. But among fishes as a 

 class, and among reptiles as a class, it is observable that, 

 speaking generally, the larger species are framed on the 

 higher types. The critical reader, who has men 



tally checked these statements in passing them, has doubtless 

 already seen that this relation is not a dependence of or 

 ganization on growth, but a dependence of growth on or 

 ganization. The majority of Exogens are smaller than some 

 Endogens ; many Endogens are exceeded in size by certain 

 Acrogens ; and even among Thallogens, the least developed 

 of plants, there are kinds of a size which many plants of the 

 highest order do not reach. Similarly among animals : 

 there are plenty of Crustaceans less than Actinia ; numerous 

 reptiles are smaller than some fish ; the majority of mam 

 mals are inferior in bulk to the largest reptiles ; and in the 

 contrast between a mouse and a well- grown Medusa, we see a 

 creature that is elevated in the scale of organization, ex- 

 ceeded in mass by one that is extremely degraded. Clearly 

 then, it cannot be held that high organization is habitually 



