of the Salmon in Fresh Water. HI 



the fibres does riot look nearly so crowded with ie, ; the fat granules are 

 much smaller and more scattered, and the masses ao the periphery of 

 the fibres are all used up. 



A comparison between the appearances of the Figures 2 and 3 

 would suggest the idea of a secreting cell during activity in the case of 

 the former, and at rest in the latter. But it is a mere analogy and 

 cannot be pushed f ,ir, as that would involve a formation of fat bv the 

 protoplasm of the cell. 



As generally stated by pathologist s, and also found in my specimens, 

 the fibres that undergo such fatty changes show indications of dis- 

 appearance of the cross stripes. Tin's loss of transverse striation is 

 usually concomitant with the appearance of marked longitudinal cleavages 

 between bundles of fibrils and also individual fibrils. Hence it would 

 appear that the obliteration, or rather obscuration, of the transverse stria- 

 tion of a fibre is due to the relationship of the individual fibrils in 

 lateral apposition being disturbed, and the intertibrillary spaces being 

 crowded with highly refractile granules of fat. This is shown by Figuie 

 6, where the section was treated with ether to remove the fat 

 granules, and thus render the fibres clearer. Now this section, when 

 loaded with granules of fat, would present a somewhat similar appearance 

 to Figure 7,* which is a typical pathological specimen of "fatty 

 degeneration." Of course the fibres in t'ue mu.scle of salmon are very 

 much coarser than those of human muscle. 



Bogdanow (I"), in an account of his research on the muscle fat in 

 horse flesh, describes that, after a single Soxhlet extraction, most of the 

 fat in the connective tissue disappears, while the muscle fibre treated 

 with 1 per cent, osmic acid stains brown (though lighter than non- 

 extracted fibres) ; this staining gets lighter with each extraction. He 

 adduces this in support of the statement that there exist two fats in 

 flesh. Muscle of fish is much more friable than horse flesh, at least 

 sections treated with ether lose all fat, as shown in 'Figure 6 ; but 

 with prolonged action of alcohol I find that all connective tissue fat 

 (even intercellular fat) disappears, but the interfibrillary fat glanules 

 are not so easily removed, .but from this it does not necessarily follow 

 that the second fat is derived from the muscle plasma, whereas any 

 attempt to prove its production by the muscle cell, owing to its 

 resemblance to milk fat, would ainonnt to " begging the question." 



Scientific scepticism is always a great help towards the establishment 

 of a firm foundation of truth. So the position assumed here is, that 

 the usual microscopical evidence on " iatty degeneration of muscle " 

 cannot be depended upon. A line of demarcation between fatty 

 degeneration and fatty infiltration can hardly be drawn with a steady 

 hand. Many cases of so-called fatty degeneration are merely such 

 interfibrillary infiltration as occurs in the salmon's muscle. Actual 

 breaking down of proteid molecules may take place, but any such state- 

 ment has to be substantiated by resul's of chemical examination. 



DESCRIPTION OF FIGURES. 



THK FIGURES ARE REPRODUCTIONS OF MICRO PHOTOGRAI-HS. 

 Fig. 1. Muscle of salmon leaving the sea, with fat-globules between fibrils. 

 Fig. 2. T.S. muscle fibres of salmon from upper reaches of river with very 



little interfibrillar fat. 

 Fig. 3. T.S. muscle fibres of salmon caught in the sea with abundance of fat in 



the fibres. 

 Fig. 4. L.S. muscle of salmon some time in the river showing little fat between 



the fibres. 

 Fig. 5. L.S. muscle of salmon caught in the sea with abundance of inter-fibrous 



fat. 

 Fig. 6. L.S. muscle of salmon treated with ether to remove fat globules to show 



apparent disappearance of transverse striation. 

 Fig. 7. L.S. human muscle in state of fatty degeneration. 



* This specimen was kindly lent by Dr. Robert Muir, Pathological Laboratory, Edin- 

 burgh University, 

 t Pfluger's Archiv., Bd. LXV. 



