156 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



have said merely refers to hydrology as au aid in the study of ichthy- 

 ology and the fisheries. 



§ 24. But the separate hydrological conditions, such as the different 

 currents of the sea, its temperature, the proportion of salt and gas con- 

 tained in the water, &c., must be studied, not only in themselves and 

 in their relation to the fisheries, but also with regard to their iutiuence 

 on the vegetable and animal life of the sea. The scientific investiga- 

 tions of the sea must therefore endeavor to find the connection betM^een 

 the different organic forms, both in a general way and more especially 

 with regard to those that are of economical value for man. Thus, with 

 regard to the herring, science ought to find out the influence which 

 the diatoms and other animalculfe exercise on it, and the conditions on 

 which their occurrence and distribution depend.^^ The vegetable and 

 animal life of the sea must therefore be studied, not only from a mor- 

 phological, physiological, descriptive, and physico-geographical point of 

 view, but also with regard to the position which each individual form 

 occupies in the great household of nature. 



§ 25. The bottom of the sea must not be forgotten, but must be made 

 the subject of a thorough scientific investigation, both as regards its oro- 

 graphical and geognostical character, not only in itself but chiefly with 

 regard to the influence which it exercises on the currents of the sea and 

 on its vegetable and animal life. 



§ 26. The extent of the different scientific investigations is thus clearly 

 given by the very character of the study of natural history, which, the 

 more scientific it is, the more it shoidd be a comparative study, because 

 nature forms a continuous whole where one link of the chain is con- 

 nected with and depends on another, so that no satisfactory^ result can 

 ever be obtained if one branch is studied as a specialty to the exclusion 

 of those with which it is connected. 



§ 27. As has been mentioned above, all such investigations of the sea 

 and the fisheries, if they are to lead to the desired result, must be car- 

 ried on simultaneously in as large a number of places as possible ; for 

 in no other way can a deep insight be gained into the hydrological con- 

 ditions of the nature of the fisheries themselves, and of their connection 

 with meteorological causes. These investigations must, therefore, as is 

 already done in meteorology, be made by the united efforts of several 

 nations. The investigation of the natiu-e of those small seas round which 

 so many of our modern civilized nations dwell — Englishmen, Dutch, 

 Germans, and Scandinavians — and which, more than any other seas, are 

 full of fishing and sailing vessels, should certainly be of such interest 

 for science, the fisheries and navigation, that there should be no delay 

 in making them. Germany has also in this respect made a beginning, 

 by sending out expeditions, and by having daily observations taken at 



"t7. MacCuUoch ^^On the herring" (The Quarterly Journal of Science, Literature, and 

 Arts. XVI. London, 1824), p. 219. 



