278 ANNUAL OF SCIENTIFIC DISCOVERY. 



deeper red, and keeps this color longer than the male ; and often in the same 

 stream there are taken white trout and salmon trout. This shows, too, that the 

 salmon trout is not the mongrel of the trout and salmon ; besides, the fecun- 

 dation of one of these fish by the other is out of the question, since the salmon 

 spawns in July and rarely in August, while the trout spawns in December. 



The coloring matter of the muscles of a salmon attracted the attention of 

 Sir Humphrey Davy ; in the work by this famous chemist, entitled Sahnonia, 

 it is said that the skin of a salmon can be discolored by ether. But even till 

 now, this coloring matter has not been isolated. It is this which we attempt 

 to accomplish. From our researches, we find this coloring matter to be of a 

 fatty nature, presenting the characteristics of a weak acid, which we call sal- 

 monic acid, and that it dissolves in a neutral oil. In order to isolate salmonic 

 acid, we used the following means : the red oil which is easily got from the 

 muscles of a salmon by a press, was agitated cold with alcohol feebly arnmo- 

 niated ; the oil then becomes colorless, and the alcohol takes the coloring 

 matter, which is separated by decomposing the ammoniacal salt with an acid. 

 The acid thus obtained is viscous, red, and presents all the characteristics of 

 a fatty acid ; it is the same in the salmon-trout as in the muscles of a salmon. 

 "We have found it in considerable quantity and mixed with oleophosphoric 

 acid in the eggs of salmon, which partly accounts for the discoloration and loss 

 of smell in the flesh of a salmon when it lays. The female of the Salmo 

 hamatus Val, does not afford as much acid, either salmonic or oleophosphoric, 

 as the common salmon (Salmo sahno Vol.] : the muscles of fish show therefore 

 in species most nearly allied appreciable differences in their composition. 



ON THE ORIGIN OF MALAKIA. 



Some interesting experiments have recently been instituted by MM. Savi 

 and Passerini, of Pisa, Italy, on the noxious qualities of some plants supposed 

 to be a source of malaria. The results of these we shall here briefly state. 



The chara, a genus of plants which grows very plentifully in the marshes, 

 exhales, especially during summer, a fetid smell, similar to that of the marshes 

 themselves. This has led some to suspect that these plants, during their 

 growth, decay, and decomposition, might be the cause of the malaria. To 

 clear up this doubt, MM. Savi and Passerini undertook a series of observations 

 on, and analyses of, the more common species, the chara vulgaris and the chara 

 flexibilis. 



They found these plants covered with an external crust of carbonate of 

 lime, the quantity of which, always considerable, diminishes successively and 

 gradually during the four months of May, June, July, and August, which are 

 precisely those in which the influence of the malaria is most strongly felt. Among 

 the other elements of the chara they detected also a fat volatile substance, 

 hitherto unnoticed, which, containing azote, has an analogy with animal sub- 

 stances, and produces the fetid smell which gave rise to these researches. 

 They named this substance puterine, from the vulgar name of putera, which 

 the Italians give to the plant. 



After examining the chara hi its living and perfect state, they submitted 

 it to putrefaction by steeping it in water. Decomposition began to show 



