396 GREAT STEPS IN ORGANIC EVOLUTION 



ante-natal connection between mother and offspring began 

 with the placental mammals; it implied an intimate living 

 together or symbiosis of parent and child that has been of 

 far-reaching importance. 



We must remember also how some amphibians achieved 

 what a few fishes essayed, getting foothold on dry land. 

 Most of the amphibian pioneers have to return to the water 

 in their breeding and early development, and the possession 

 of dry land must be put to the credit of reptiles, and asso- 

 ciated with what seems at first sight a mere internal detail, 

 — the development of an ante-natal robe that secures breath- 

 ing through the egg-shell. And just as amphibians mark the 

 transition from water to dry land, which the reptiles per- 

 fected, so the extinct flying dragons or pterodactyls pointed 

 from a great distance to that mastery of the air which birds 

 and bats perfected, — each type, however, it is interesting 

 to notice, presenting a different solution of the problem of 

 flight. 



As we have already seen, the great structural advances 

 are associated with progressiveness of behaviour. Many an 

 infusorian has a very complex life and orders its goings very 

 perfectly, but the range is obviously narrower than that of 

 a spider and the resources are fewer. The behaviour of 

 ants and bees is very complex and on the instinctive line 

 very effective, we may almost say, unsurpassable. But the 

 range is narrower than that of a dog, and the resources are 

 fewer. It is in the big-brained birds and mammals that we 

 find the most convincing evidence of an inner mental life 

 of subjective experimenting, which we call in ourselves 

 perceptual inference or intelligence. Very interesting also 

 is the fact that as an organism attains to more or less 

 intelligent mastery of its environment, it is able to practise 



