EELATION BETWEEN STEUCTUEE AND FUNCTION. 19 



nerve-trunks of the region — as, for instance, in the brachial 

 reigon. The brachial and lumbo-sacral plexuses are an 

 anatomical result of the greater degree of overlap, especially 

 in the distribution of the motor part of their spinal nerves, 

 obtaining in the limbs as compared with other, e.g., the 

 trunk regions of the body. 



Enough has been said, I imagine, to let us see how little 

 light is thrown upon the function and uses of the limbs by 

 study of their segmental architecture. It is especially when 

 the anatomist confines his attention to minute examination 

 of one limited group or type, that he seems to become 

 most prone to dogmatise concerning function, and his 

 arguments have to be received, unless checked by actual 

 experiment, with the extremest caution. In a certain 

 sense, it would seem that the creative power of nature can 

 mould with such superfluity of resource the, to us, who 

 cannot construct it, pricelessly valuable material that 

 heredity and life bequeath, that she has various ways 

 open for compassing the same required end. Thus a seg- 

 ment more or a segment less offers little difficulty to her. 

 The individual with a segment less or segment more 

 betrays neither his defect nor his surplus by any trace of 

 disturbance of function ; his idiosyncrasy goes unsuspected 

 either by himself or his neighbours, physiologists and 

 morphologists though they may be. When the "how" of 

 the processes of function and of structure is nearer answer 

 than at the present time, this may appear to us less strange 

 than now. But for the present it does seem clear that the 

 aws of morphological structure and of physiological struc- 

 ture, though they must be fundamentally correlated, are 

 much more different than many are accustomed to 

 think of them and say. The width of the chasm between 

 the two is probably best felt by the zoologist who holds in 

 view in his mind's eye the vast range of comparative 



