790 



THE POPULAR SCIENCE MONTHLY. 



whether they will or not, and often against their will. The amount 

 of interest which these impressions awaken is determined by the 

 coarser pains and pleasures which they carry in their train or by 

 mere curiosity ; and reason deals with the materials supplied to it as 

 far as that interest carries it, and no further. Such common knowl- 

 edge is rather brought than sought ; and such ratiocination is little 

 more than the working of a blind intellectual instinct. It is only 



when the mind passes be- 

 cp yond this condition that it 



begins to evolve science. 

 When simple curiosity pass- 

 es into the love of knowledge 

 as such, and the gratification 

 of the aesthetic sense of the 

 beauty of completeness and 

 accuracy seems more de- 

 sirable than the easy indo- 

 lence of ignorance ; when 

 the finding out of the causes 

 of things becomes a source 

 of joy, and he is accounted 

 happy who is successful in 

 the search, common knowl- 

 edge passes into what our 

 forefathers called natural 

 history, whence there is but 

 a step to that which used 

 to be termed natural philos- 

 ophy, and now passes by the 



Fig. 1. AsTAcrs FLtmATii.is.-Thc third or external max- ^^me of physical Science. 

 ilUpedeof the leftside(x3). f, lamina, and 6r, bian- « In this final State of 



chial filaments of the podobranchia ; cxp, coxopodite ; 



cxs, coxopoditic set* ; bp, batipodite ; ex, exopodite ; knowledge the phenomena 

 ip, ischiopodite ; mp, meropodite ; cp, carpopodite : ^ • 



pp, propodite ; dp, dactyiopodite. ot nature are regarded as 



one continuous series of 

 causes and effects ; and the ultimate object of science is to ti'ace out 

 that series, from the term which is nearest to us, to that which is at 

 the farthest limit accessible to our means of investigation. 



" The course of nature as it is, as it has been, and as it will be, is 

 the object of scientific inquiry ; whatever lies beyond, above, or below 

 this, is outside science. But the philosopher need not despair at the 

 limitation of his field of labor ; in relation to the human mind Nature 

 is boundless ; and, though nowhere inaccessible, she is everywhere un- 

 fathomable." 



It is, then, with the object of arriving at a satisfactory conclusion 

 as to the crayfish's place in nature, and to educe from the study of it 

 such conclusions as may tend to throw light on the place in nature of 



