298 ORDER AND SUCCESSION OF LIFE, 



in full force now ; palaeontology declares they were as uni- 

 versally energetic in bygone epochs. 



Besides these obvious arrangements and inter-relations 

 of life, there is also grade or degree of organisation some 

 orders being more simple in structure and fitted for lower 

 functions, others being more complex and fitted for the 

 higher offices of vitality. The lichen incrusting the rock or 

 the sea- weed clustering the shelving reefs of the sea- shore, 

 and devoid of stem and leaf, is a lowlier organism than 

 the clubmoss or tree-fern ; and these again are less highly 

 organised than the true timber-tree, with its complex de- 

 velopment of trunk, branches, leaves, flowers, and fruits. 

 The sponge, rooted plant-like to the rock, is clearly a lower 

 phase of animal life than the coral or star-fish ; and these 

 again are less highly organised than the crabs and shell-fishes. 

 Animals like the star-fishes, crabs, and shell-fish, devoid of 

 backbone and bony skeleton (the Invertebrata\ are obvi- 

 ously lower in the scale of being than the fishes, reptiles, 

 birds, and mammalia (the Vertebrata); and even among 

 these vertebrates the cold-blooded water-breather is inferior 

 to the warm-blooded air-breather the fish on a lower stage 

 than the reptile, the reptile than the bird, and the bird 

 than the mammal. Still more, the marsupial or pouched 

 mammal, bringing forth immature young and carrying them 

 about for months, is less highly organised than the placen- 

 tal or true mammal, which gives birth to fully developed 

 young ; and among the true mammals themselves there are 

 manifestly various grades of organisation the whales are 

 lower than the ruminants, the ruminants than the carnivora, 

 the carnivora than the monkeys, and the monkeys than man. 

 And whatever may have been the abundance or develop- 

 ment of life during the geologic epochs, we may pre- 

 sume that such grades and distinctions have ever per- 

 vaded the whole vital scheme high and low, low and 



