THE SALT-WATER FISHERIES OF BOHUSLAN. 163 



others into a whole. The last-meDtioned work is no less important than 

 the former, and is actually the really scientific portion of the work. 



7. Even in biology there are many questions which cannot be satis- 

 factorily answered by om person, but which demand the systematic work 

 of several naturalists, just as is the case in meteorology. That this is 

 specially necessary with regard to our subject will be evident when we 

 think of the complete series of observations which are needed — observa- 

 tions referring not only to biology, but also to meteorology, hydrology, 

 &c.; for only hy making full observations in all these directions can we 

 arrive at any satisfactory result. And in order to have these observa- 

 tions as full and systematic as possible there should be a number of sta- 

 tions working according to one and the same plan.^^ 



Although the time is certainly very far distant when sufficient obser- 

 vations will have been collected to furnish the necessary material for a 

 satisfactory scientiiic solution of our problem, we shall see from the fol- 

 lowing that, as far as Bohusltin is concerned, a complete meteorological 

 station would be extremely useful during a rich fishing-season. Those 

 who devote themselves to the herring-fisheries would gain an increased 

 knowledge of the herring, its mode of life, and its migrations, and their 

 dependence on the changes of the weather, and such a knowledge would 

 certainly be of great practical use to them. 



S. In order to gain a correct view of the causes of the irregularities 

 in the mode of life and the migrations of the herring, it is specially neces- 

 sary to get as complete a knowledge as possible of the influence which 

 physical and biological causes exercise on the herring. 



In treating this very difficult and but little known subject it must not 

 be forgotten that hitherto fishing, carried on as a trade, has been almost 

 the only means of observing the influence of such causes ; and as fish- 

 ing is only carried on at those seasons and places and with those imple- 

 ments which promise the greatest success, it will be clear how incom- 

 plete and unreliable our knowledge must be. Great caution is required 

 in gathering and receiving information, for mere fanciful and hypothet- 

 ical theories lead us only forther away from our true object. This part 

 01 my work had chiefly to be confined to the collecting and arranging of 

 all the data found in literature. 



0. We must first consider the influence which the sun and the moon 

 exercise. The sun produces day and night and the four seasons. The 

 changes produced by the turning of the earth round its axis and round 

 the sun act not only through the greater or smaller quantity of light, but 

 in a still higher degree thi'ough the differences of temperature and the 

 general changes in the weather which they produce. Attempts have 



=• Those who have to do this preparatory work should be fully impressed with the 

 fact that the result of their labor will chieHy beuefit the scientists of the future. They 

 must, therefore, sacrifice their own scientific vauity and the hope of reaping the fruits 

 of their labor, but be satisfied to know that it will form part of the foundation of the 

 science of the future. This self-sacrificing work may well be said to ennoble him who 

 engages in it, and who deserves the esteem and gratitude of humanity. 



