6 ZOOLOGY 



first instance rv a breathing, being," but the significance of the 

 word was soon extended so as to include all beings which 

 actively moved, such as insects, even if they did not obvi- 

 ously breathe air. The wider idea of life was connected by 

 the ancients with the idea of growth, and the proper name 

 for the science of life would be Physiology, a word com- 

 pounded of the termination -logia and the word phiisis, 

 which signified growth in the widest sense. The good old 

 word physiology had however been used for so long in con- 

 nection with medicine to denote the science of the life of man 

 that Huxley thought it necessary to coin a new word, Biology, 

 to denote life in its widest sense. The etymology of the 

 term is bad Greek, for bios never denoted " life " in the 

 general sense in that language. However, all confusion of 

 thought was avoided by the new term, and we must forgive 

 its faulty derivation. As the idea of animal is that of a 

 moving being, so the idea of life is that of something that 

 grows. These ideas were taken over from primitive times 

 by that orderly careful type of thinking characteristic of our 

 own day, and denominated science ; by it they have been 

 recast, because not everything that moves is an animal for 

 instance, a volcanic bomb or a shooting star is not included 

 in the term nor is everything that grows living for instance, 

 a snowball rolling down a snowy hill or a crystal suspended 

 in its mother liquor both grow, but neither is regarded as 

 alive. 



Life is defined for science as the state or condition of a 

 being which grows and which reproduces itself. The growth 

 postulated is however very different from that of the snow- 

 ball or of the crystal. In these two cases increase in size 

 results from the addition of new matter, which is laid on in 

 successive layers round the original matter which persists as 

 the core. But in the case of a being which has life or, as 

 we term it, a living being or organism growth results from 

 the intercalation of new material between the interstices of the 

 finest particles of the old: this is termed growth by intus- 

 susception. In this way the child grows to manhood ; so that 

 to take the face, for instance, although the absolute size of the 

 features is more than doubled, their general proportions relative 

 to one another remain the same. By reproduction is meant 



