OUE ECONOMIC SEA FISHES. 403 



present themselves there is a loose tendency to phylogenetic 

 speculation. This last may temporarily satisfy our ignorance, 

 but yet is an unstable platform to rest on where practical issues 

 are at stake. 



Necessarily many of the researches now in progress appear 

 superfluous or insignificant, but science abounds with instances 

 of seeming trifles leading to unexpected beneficial results. It 

 cannot be affirmed with absolute certainty that there has been 

 material increase in British fisheries since the advent of the labora- 

 tory and out-of-door investigations. But there is no gainsaying the 

 fact that a sound foundation has been laid for a study of their 

 economy; witness Mcintosh and Cunningham's volumes afore- 

 said. Take, for example, investigations of embryotic and post- 

 larval conditions : it is a long jump from to over eighty species 

 to be recorded. 



The spawning grounds, the periods of spawning, and the 

 varied lengths of the spawning process in different fish, are in 

 many cases far better understood, whilst it is pretty well 

 proved that temperature has a manifest effect on the duration 

 of hatching, a fact established by Higginbotham (1850)* in 

 experiments on the Frog, and now shown likewise to be the case 

 in fish-eggs. Migratory habits are gradually getting law-evolved. 

 As to cases in point, there is that of the to-and-fro movement 

 from offshore to inshore, and the reverse. Of a certainty it can 

 now be said of some fish, that on hatching the larva and post- 

 larva uniformly and gradually make for shore or shallow water, 

 there to spend their young stage, to retreat again to deep water on 

 becoming older, and this in a definite course. There is regular 

 congregation and migration during spawning season, partial dis- 

 persion thereafter. Search for food assuredly induces wandering 

 habit, and atmospheric changes drive to greater depths. The 

 factors conducing to erratic wholesale emigration, or the sudden 

 departure from a long frequented spot or area, each fish's par- 

 ticular enemies, and their diseases aside from effects of parasites, 

 are still subjudice. 



Probably there is no more promising field still requiring 

 exploration on British shores than that of the surface organisms, 



* The circumstance was known, however, to Spallanzani, Kusconi, and 

 others, in Amphibia a century ago. 



