282 THE WORLD OF LIFE chap. 



better adapted to resist their attacks ; and when the new type 

 had become well established it quickly replaced the earlier 

 forms ; and the highly specialised reptiles, unable to obtain 

 sufficient nourishment from it, and being also subject to the 

 attacks of Carnivora of increasing power, and perhaps to some 

 adverse climatic changes, quickly disappeared. Then came 

 the turn of the Mammalia, the birds, and the more specialised 

 insects, which, during this vast period, had been slowly 

 developing into varied but always rather diminutive forms, 

 the birds and mammals feeding probably on insects, roots, 

 and seeds ; but, in proportion as the reptiles disappeared, 

 they were ready to branch out in various directions, occupy- 

 ing the many places in nature left vacant by these animals, 

 and thus initiated that wonderfully varied mammalian life 

 which throughout the whole Tertiary period occupied the 

 earth's surface as completely, and almost as exclusively, as 

 the reptiles had done during the middle ages of geological 

 time. 



The reactions of insects and flowers are universally 

 admitted, as are those between birds and fruits ; but the 

 broader aspect of this reaction between animal and plant 

 life as a whole has not, I think, received much attention. 

 It does, however, seem to throw a glimmer of light on the 

 very puzzling facts of the vast development of Secondary 

 reptilian life, the apparent arrest of development of mammals 

 during the whole vast period, and the rapid and abundant ; 

 outgrowths of the higher types both of plants and of | 

 Mammalia in the Tertiary age. 



The complete metamorphosis, broadly speaking, of both 

 plant and animal life, on passing from the former to the 

 latter epoch, is most startling. Such a change was, however, 

 absolutely essential, not only for the production of the higher 

 Mammalia and intellectual man, but also to provide for the 

 infinitely varied needs of man's material, moral, and aesthetic 

 development. The immensely varied plant-group of phanero- 

 gams has served to unlock for his service the myriad 

 potentialities which lay hidden in protoplasm — the mysterious 

 physical basis of all life. To this vast series of herbs and 

 shrubs and forest-trees he owes most of the charms, the 

 delicacies, and the refinements of his existence — almost all 



