NATURAL HISTOKY — ZOOLOQY. 21& 



with these conclusions, deducible from his researches and obser- 

 vations : 



" 1. That the gastric juice, and probably the other fluids concerned 

 in the function of digestion in fishes, are not secreted till the secre- 

 ting organs are stimulated by the presence of food — a conclusion in 

 harmony with a pretty general physiological law, and in accordance 

 with what has been best ascertained respecting the gastric juice in 

 other animals. 



"2. The probability that the gastric fluid — a fluid with an acid 

 reaction — is less potent in the instance of fishes as a solvent 

 than the alkaline fluid of the appendices pyloricce ; and that even 

 as regards the gastric fluid, its acidity is not essential to it, as 

 its action does not appear to be arrested when it is neutralized 

 by the presence of articles of food abounding in carbonate of lime. 



" Lastly, as a corollary from the first, may it not be inferred that 

 the migratory species of the salmonidas, such as the salmon and sea 

 trout, which attain their growth and become in high condition in the 

 sea, there abundantly feeding and accumulating adipose matter, 

 though not always abstaining in fresh water, which they enter for 

 the purpose of breeding, are at least capable of long abstinence 

 there without materially suffering? And may not this be owing to 

 none of their secretions or excretions, with the exception of the mdt 

 of the male and the roe of the female, being of an exhausting kind ? 

 And further, owing to the empty and collapsed state of the stomach 

 and intestines, are they not, when captured, less subject to putrefac- 

 tion, and thus better adapted to become the food of man V — See 

 Edinburgh New Philosophical Journal, No. 22. 



SALMON IN THE THAMES. 



In the autumn of last year, two Salmon were taken in the Thames, 

 off Erith. These fish had evidently entered the river (with others, _ 

 doubtless, which have escaped capture) with the view of pushing up 

 to the spawning-grounds. Salmon in the latter end of October are 

 heavy in spawn, and, even in a well-stocked river, should not be 

 taken. In the river they might have been most valuable, and have 

 added in forming a small nucleus for breeding purposes. These fish 

 might have spawned in the river, and probably would. It would 

 have been two years before the fry would have required to come 

 down again through the muddy pool to the sea. By that time the 

 water might have been pure enough to allow them to do so safely ; 

 and in all probability some hundreds of fine grilse would speedily 

 have returned to gladden our eyes and re-stock our river ; and the 

 salmon would once more have been naturalized in the Thames, without 

 costing anyone one sixpence for spawn-boxes, watchers, &c, a pro- 

 cess which, after all, too often forms but a doubtful experiment. 

 Now, the Act of Parliament which regulates the close-seasons on the 

 Thames, says that no one shall capture salmon after the 10th of 

 September, nor before the 25th of January succeeding, under a 

 penalty of 51., which penalty the captors of the above fish have 

 clearly rendered themselves liable to. The fish, we hear, were sent 



