ANIMAL DEVELOPMENT. 38& 



CHAPTER XV. 



PHENOMENA OF ANIMAL LIFE. 



Distinction between tbe Kingdoms of Nature Progress of Ani- 

 mal Life Sponges Polypes Infusoria Animalcula 

 Phosphorescent Animals Annelidans Myriapoda Ani- 

 mal Metamorphoses Fishes Birds Mammalia Ner- 

 vous System Animal Electricity Chemical Influences 

 Influence of Light on Animal Life Animal Heat Mecha- 

 nical Action Nervous Excitement Man and the Animal 

 Races, &c. 



" A STONE grows ; plants grow and live ; animals grow, 

 live, and feel/' Such .were the distinctions made by 

 Linnseus, between the conditions of the three kingdoms 

 of nature. We cannot, however, but regard them as 

 in all respects illogical. The stone a solid mass of 

 unorganized particles enlarges, if placed in suitable 

 conditions, by the accretion of other similar particles 

 around it ; but it does not, according to any meaning 

 in which we use the word, (/row. Plants and animals 

 grow ; and they differ, probably, only in the phenomena 

 of sensation. Yet, the trembling mimosa, and several 

 other plants, appear to possess as much feeling as 

 sponges and some of the lower classes of animals. By 

 this definition, however, of the celebrated Swedish 

 naturalist, we have a popular and simple expression of a 

 great fact. 



As we have only to examine the question of the 

 agency of the physical forces upon animal life, we must 

 necessarily confine our attention to the more striking 

 phenomena with which science has made us acquainted : 



