66 LIFE-HISTORY OF A FISH FROM A PELAGIC EGG. 



In the foregoing remarks a few of the leading features of 

 the life-history of a food-fish have been but touched on, for the 

 subject is one of vast extent, and some of the points embraced 

 in it are by no means easily solved. We have only earnestly 

 entered on the study of the subject in this country within the 

 last few years, and much yet remains to be done, even in some 

 of the most common marine fishes. However, the zoological 

 investigator is here stimulated by the fact that all his labours 

 directly bear on the public welfare, for it need hardly be pointed 

 out that a thorough knowledge of the development and life- 

 histories of our food-fishes is the first step to sound legislation 

 and effective administration. The State has in past years spent 

 princely sums on more or less pure science, as in the memorable 

 voyage of the Challenger. There can be no doubt, notwith- 

 standing the recent opposition, that at the present moment 

 the public interests demand a searching and long-continued 

 inquiry nearer home, viz. the exhaustive investigation of all 

 that pertains to the food-fishes of our shores, since the problems 

 connected therewith affect the prosperity of so large a portion 

 of the population. 



The difference between the larval cod and the young salmon 

 just hatched is striking. The former, that is, the young cod, 

 is in a very rudimentary condition, not only in size but in 

 structure. For instance, it is devoid of mouth and vent, and 

 though the heart pulsates, it, as our colleague, Prof. Pettigrew, 

 observed, is devoid of blood, and there are no blood-vessels. 

 Those, therefore, who thought that the heart in animals 

 contracted from the stimulus of its living blood, would have 

 here found little support. The tiny larval cod of about 4 mm. 

 is so fragile that it can be handled with difficulty, and it 

 would seem as if a breath would destroy it. On the other 

 hand the newly-hatched salmon has attained great complexity, 

 and is about three-fourths of an inch in length, while several 

 days may be spent in delineating its elaborately branched 

 blood-vessels through which the blood-discs may be followed 

 as they swiftly circulate in the transparent tissues. 



