50 Thomas Henry Huxley 



his mind b}- consideration of many of the forms of 

 marine life, notably compound structures like the Por- 

 tuguese man-of-war, and creatures like the salps, which 

 form floating chains often many yards in length. He 

 explained that the word individual covers at least three 

 quite different kinds of conceptions. There is, first, 

 what he described as arbitrary individuality, an indi- 

 viduality which is given by the mind of the observer 

 and does not actually exist in the thing considered. 

 Thus a landscape is in a sense an individual thing, but 

 only so far as it is a particular part of the surface of 

 the earth, isolated for the time in the mind of the per- 

 son looking at it. If the observer shift his position, 

 the range of the landscape alters and becomes some- 

 thing else. Next there are material, or practicall}' 

 accidental individual things, such as crystals or pieces 

 of stone; and, lastly, there are living individuals which, 

 as he pointed out, were cycles. All living things are 

 born into the world, grow up, and die, and it was to 

 the cycle of life, from the &%% to the adult which pro- 

 duces eggs, that he gave the name individual. In a 

 simple animal like Hydra there is no diflSculty in accept- 

 ing this plain definition of individuality; but Huxley 

 went on to compare with Hydra a compound creature 

 like the Portuguese man-of-war, which really is com- 

 posed of a colony of Hydra-like creatures, the different 

 members of the colony being more or less altered to 

 serve different functions. All these have come from 

 the branching of a single simple creature produced from 

 an ^g%, and to the whole colony Huxley gave the 

 name of zoological individual. The salps give a still 

 wider interpretation to this view of individuality. The 

 original salp produced from the 0.%^ gives rise to many 

 salps, which may either remain attached in a chain, or, 



