146 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



tious and imposing scientific systems. It must be remembered that in 

 science, as little as anywhere else, is there a royal road to reach one's 

 object, and it is often nothing but vanity which has led persons to build 

 such air-castles and call them scientific achievements. 



§ 8. The difficulty of finding the causal connection is also much greater 

 in that portion of natural history which is most important for our pur- 

 pose, that is, the so-called physiology of relations, than in anatomy 

 or the history of natural development. The anatomist, after having 

 dissected a few specimens and found them to agree, may generally be 

 certain that he has ascertained their normal condition, and that any de- 

 viations from this which may possibly be discovered in the future must 

 be considered abnormal. The anatomist can and must often be satis- 

 fied with examining only a few specimens, and may from these draw 

 a tolerably certain conclusion ; but this would not answer in the physi- 

 ology of relations Avith its many changes and irregularities. Here it is 

 necessary to employ every means at our command for taking the greatest 

 possible number of observations, and then, after critically examining 

 their reliability, aud instituting the most careful comparisons between 

 them, and by using every method of induction, analogy, and hypothesis 

 for reaching a conclusion, to obtain the most probably or at least approx- 

 imately correct view. Thus the demonstrative certainty gradually de- 

 creases in the physico-mathematical scieuces in proportion as we depart 

 from the abstract, outward forms of objects, or from general laws or 

 component parts, and enter the domain of organic nature, which becomes 

 more difficult for the naturalist the more life itself comes into question. 



§ 9. Eegarding the general view of nature and the diflerent methods 

 of explaining its phenomena, it must be said that a really scientific ex- 

 planation, going back to final causes, is scarcely possible, as soon as from 

 general views we enter upon details. An explanation from absolutely 

 certain causes, carried through consistently, must always move in a 

 circle, because the world is a whole, developing systematically, and as 

 the various phenomena of nature mutually depend upon each other, so 

 that one phenomenon may depend upon another which follows it, whilst 

 we from our youth up are accustomed to draw a conclusion by advancing 

 from a jmst hoc to an ergo proper hoc. The aim of natural science is, 

 therefore, to be as free as possible from teleological and mechanical prej- 

 udices and methods of explanation, and to endeavor to show the actual 

 connection between the different phenomena, and not to draw philo- 

 sophical a irriori conclusions as to their absolute necessity. 



On the material which has been acquired in this manner every one 

 must, according to the best of his ability, base his more or less philo- 

 sophical theories, being careful, however, to keep these latter strictly 

 separate from the facts. 



§ 10. The sources of knowledge to which we are directed as regards 

 fish, fishing- waters, and fisheries, are: literature, the experience of fish- 

 ermen and superintendents of fislieries, and direct observations and 

 experiments. 



