28 THE PHYSICAL KINSHIP 



skulls and spinal columns, red blood, brains, and 

 dorsal cords ; and in possessing two eyes, two ears, 

 nostrils, and mouth opening out of the head. 



And finally all animals, including man, are 

 related to all other animal forms by the great 

 underlying facts of their origin, structure, com- 

 position, and destiny. All creatures, whether they 

 live in the sea, in the heavens, or in subterranean 

 glooms ; whether they swim, fly, crawl, or walk ; 

 whether their world is a planet or a water-drop ; 

 and whether they realise it or not, commence exist- 

 ence in the same way, are composed of the same 

 substances, are nourished by the same matters, 

 follow fundamentally the same occupations, all do 

 under the circumstances the best they can, and all 

 arrive ultimately at the same pitiful end. 



VI. The Meaning of Homology. 



The similarities and homologies of structure 

 existing between man and other animals, and be- 

 tween other animals and still others, are not acci- 

 dental and causeless. They are not resemblances 

 scattered arbitrarily among the multitudinous 

 forms of life by the capricious levities of chance. 

 That all animals commence existence as an egg 

 and are all made up of cells composed of the 

 same protoplasmic substance, and all inhale oxygen 

 and exhale carbon dioxide, and are all seeking 

 pleasure and seeking to avoid pain, are more than 

 ordinary facts. They are filled with inferences. 

 That vertebrate animals, differing in externals as 

 widely as herring and Englishmen, are all built 



