THE TRIGGER-FISH 



category: the words armour, helmet, sword, which 

 we use because of the obvious resemblance, seem to 

 make us assume an identical role in both cases. But 

 when we do this, we disregard natural conditions ; life, 

 in its processes, has no need of such an arsenal of 

 weapons. It is true that there is sometimes a pro- 

 tective covering, and that sometimes too we find the 

 capacity to attack and pierce and bite. But the actual 

 purpose here is subordinate to the necessity of having 

 in or around the body a skeleton, an apparatus made 

 up of hard pieces able to support the soft parts and 

 prevent them from collapsing. This is the necessity 

 upon which the others depend. The main need is 

 to support the organism, to keep it in a state of equi- 

 librium and allow its cavities room for expansion, to 

 provide opportunity to fulfil its functions. The rest 

 comes afterwards, as an entirely secondary considera- 

 tion, only if circumstances permit of this further 

 utilization. 



The presence of a supporting apparatus, a skeleton, 

 is a most frequent occurrence, so frequent that we 

 tend to take it for granted. Animals completely devoid 

 of it are comparatively rare. Sometimes the structure 

 simply surrounds the body; sometimes it is em- 

 bedded in its substance; sometimes both one and the 

 other. The skeleton may be external or internal, or 

 in two parts, one internal and one external. The 

 important fact is that it exists, that it does serve to 

 support the soft tissues, and, if necessary, reinforce 

 the muscles. Its function is general, and it is observed 

 in the simplest of creatures. 



Its presence is a mark of the essential, characteristic 

 quality of living matter, that of creating and building 

 up symmetrically. Life is of itself an association of 

 energies which manipulate the particles of matter and, 

 at various stages, give them forms, which ultimately 

 take shape as organs and individuals. Every creature 

 has a metabolism of its own, a quality of assimilation 



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