THE STORY OF ANIMAL LIFE II 



zoologists had greatly to modify their ideas of the 

 animal world. Still more was this the case after- 

 wards, when it was found that all animals were 

 built up of minute parts much resembling these 

 microscopic animals in their main features. To 

 these unit parts, of which all animal bodies are 

 composed, the term " cell " is applied. The name 

 of cell is not very descriptive of these units in the 

 animal body, but correctly describes the unit of 

 plant structure. In certain important essential 

 particulars both, however, are alike. Nowadays 

 we are not content to describe the grouping and 

 external features of cells; their minute structure 

 also is made a subject of research and inquiry, 

 and affords a field for most of the fashionable 

 speculations of our own day. 



How great has been the progress made by the 

 science of zoology since the eighteenth century 

 may be estimated from the following quota- 

 tion: 



" I remember," says the late George J. Ro- 

 manes (in his book called " The Scientific Evi- 

 dences of Organic Evolution "), "once reading a 

 very comical disquisition in one of Buffon's works 

 on the question as to whether or not a crocodile 

 was to be classified as an insect ; and the instructive 

 feature in the disquisition was this, that although 

 a crocodile differs from an insect as regards every 

 conceivable particular of its internal anatomy, 

 no allusion at all is made to this fact, while the 

 whole discussion is made to turn on the hardness 

 of the external casing of a crocodile resembling 

 the hardness of the external casing of a beetle; 

 and when at last Buffon decides that, on the 

 whole, a crocodile had better not be classified as 

 an insect, the only reason given is, that as a croc- 



