292 CHAPTERS ON EVOLUTION. 



11 individual," when he remarks : " The idea of individuality which 

 we recognise throughout the animal and vegetable kingdoms, is 

 derived from ourselves, conscious individuals, and from our corporeal 

 structure and that of the higher brute animals. This structure is a 

 whole from which no part can be abstracted without mutilation. 

 Each individual is an independent organism of which the component 

 parts are reciprocally means and ends." . 



But another method of viewing the personality of the animal 

 is found in the deductions of physiology. Not "what it is," 

 but " from what it has originated," is the test of physiological 

 individuality. That alone, in physiological eyes, is an " indi- 

 vidual" animal which is the total result of the full development 

 of a single egg. Whatever a single egg becomes, in other words, 

 represents the individual animal or plant. Testing some of the 

 examples already noted by this criterion, we may readily enough 

 distinguish the true individuality of the animal races we have 

 passed in review. With, respect to the personality of the higher 

 animals, this test is susceptible of the plainest illustration. Each 

 quadruped, bird, reptile, fish, oyster, &c. springs from a single egg. 

 When each of the bodies in question has been formed, we know 

 that the full development of the egg or germ has been attained. 

 Hence each of the aforesaid animals is an " individual " pure and 

 simple, when judged by the standard of its representing the total 

 result of a single germ-development. With the other illustrations, the 

 case should be equally clear. A zoophyte (Fig. 197, 2) and a sea- mat 

 (Fig. 190) spring each from a single egg, and the process of budding 

 gives to each the plant-like form and the colonial organisation familiar 

 to us in these beings. Hence the whole zoophyte, and the sea- mat 

 in Mo, are " individuals." What then, it may be asked, are the separate 

 members of either colony ? Not " individuals " for they merely repre- 

 sent parts of a single egg's development but "zooids " is the biological 

 reply ; comparable, it may be, to separate-** organs " and " parts " in the 

 higher animal, but not constituting of themselves "individual" person- 

 alities. The cases of the gregarina (Fig. 183) and sponge (Fig. 187) 

 are each resolvable without difficulty on the premisses just indicated. 

 The single gregarina, arising from a true process of development, is 

 a single individual, but the divided gregarina represents a compound 

 personality. The whole sponge, arising as it does from an egg, is an 

 " individual ;" and if each of its protoplasmic units be held to be not 

 merely a cell, but a semi- independent and amoeba-like organism, the 

 sponge is a " compound individual " in addition. So also with a tape- 

 worm (Fig. 191) or other allied organism. The whole " worm" is one 

 compound " personality," or one " individual," because it has arisen 

 from a single egg, and because it represents the full development of that 

 body. So likewise with the hydra (Fig. 188). Arising from a single 



