D4 Investigations on the TAfe- History 



should be submitted to artificial gastric digestion, by which the muscle 

 fibres are dissolved and the fats liberated. These may then be 

 removed by shaking the fluid with ether. 



The muscle, ovaries, and testes of the salmon after preservation in 

 spirit are readily reduced to a very fine state of subdivision, and have 

 not the tough, fibrous consistence of horse muscle. The ether in 

 Soxhlet's apparatus has thus a much better chance of completely 

 recovering the fats. But to test the method against Dormeyer's, the 

 following experiment was performed on Salmon 44 : 



Ovaries. 38 grms., treated in the usual way yielded 3-841 grins, 

 of extract in Soxhlet's apparatus after two days' extraction. The 

 residue was subjected to peptic digestion for 12 hours, and yielded a 

 brown fluid and a copious residue. The fluid was filtered off, and the 

 residue and paper well washed with ether. The filtrate was extracted 

 with ether in a separation funnel. On distilling and evaporating the 

 ether, 0-022 grm. of residue was obtained *54 per cent, of the total 

 extract. 



Muscle. Of the thick 44 grins, and of the thin 35 grins, were treated 

 in the same way. The residue after digestion was very small in amount. 

 The following are the results : 



In thick, 0-23 per cent, of ether extract. 

 In thin, 0-13 per cent, of ether extract. 



Soxhlet's method as employed by us may thus be considered to give 

 quite satisfactory results in the case of the muscle, and somewhat too 

 low results in the case of the ovaries, but the difference is so small that 

 in calculating the percentage of fats in the ovaries the Soxhlet's extrac- 

 tion gives less than O'l per cent, less than Dormeyer's method. 

 Soxhlet's method, 10-107 per cent.; Dormeyer's method, 10*166 per 

 cent. For our purpose the accuracy of the method is amply sufficient. 



The ether extracts after weighing were preserved in small flasks, and 

 in some the amount of fatty acids were determined by Kossel and 

 Oebermiiller's method (Ztsch. f. phys. Chem. Bd. xiv. 599), while in 

 others the lecithin was estimated in the usual way. 



AMOUNT OF FATTY ACIDS. 



The following determinations show the amount of fatty acids present 

 in the ether extract of the muscle, and indicate that it is very largely 

 composed of ordinary fats : 



