206 THE STUDY OF ZOOLOGY vii 



complex is everywhere evolved out of the simple. 

 Every animal has at first the form of an egg, and 

 every animal and every organic part, in reaching 

 its adult state, passes through conditions common 

 to other animals and other adult parts ; and this 

 leads me to another point. I have hitherto 

 spoken as if the lobster were alone in the world, 

 but, as I need hardly remind you, there are 

 myriads of other animal organisms. Of these, 

 some, such as men, horses, birds, fishes, snails, 

 slugs, oysters, corals, and sponges, are not in the 

 least like the lobster. But other animals, though 

 they may differ a good deal from the lobster, are 

 yet either very like it, or are like something that 

 is like it. The cray fi,sh, the rock lobster, and the 

 prawn, and the shrimp, for example, however 

 different, are yet so like lobsters, that a child 

 would group them as of the lobster kind, in contra- 

 distinction to snails and slugs ; and these last again 

 would form a kind by themselves, in contradis- 

 tinction to cows, horses, and sheep, the cattle kind. 



But this spontaneous grouping into " kinds " is 

 the first essay of the human mind at classification, 

 or the calling by a common name of those things 

 lhat are alike, and the arranging them in such a 

 manner as best to suggest the sum of their like- 

 nesses and unlikenesses to other things. 



Those kinds which include no other subdivisions 

 than the sexes, or various breeds, are called, in 

 technical language, species. The English lobster 



