334 FATS. GLYCOGEN. . [BOOK I. 



Fats. 



The connective tissue which separates the muscular bundles 

 always contains some fat-cells, and as it is impossible to separate the 

 muscular fibres absolutely from these, we cannot readily determine 

 the amount of fat which belongs to the isolated muscular fibres. 

 There is reason to believe, however, that quite independently of the 

 fat-cells of the connective tissue of muscle, the muscular fibres con- 

 tain fat which they give up to ether ; we know nothing, however, 

 either as to its amount or composition. 



In phosphorus poisoning a fatty degeneration of muscle occurs, 

 similar to that observed to occur as an idiopathic affection, specially 

 affecting the muscular substance of the heart. In all probability, 

 in this as in other cases, the fatty degeneration is an evidence of 

 impeded nutrition (probably of imperfect oxygenation) of the tissue. 



Glycogen. (C 6 H 10 5 ) u . 



This body, which will be treated of fully in connection with the 

 liver, is a constant ingredient of the living muscular tissue. 



It was at first supposed to be only present in the muscles of the 

 embryo 1 , but it was afterwards shewn to occur in muscles of adult 

 animals under certain conditions, and later still it was found to 

 be constantly present by Nasse 2 , Briicke, Abeles and others. 



As the glycogen of muscle, on the cessation of the 

 separating vitality of the tissue, is very rapidly converted into 

 and deter- sugar, in order to separate muscle-glycogen the tissue 

 mining the must, whilst yet living, be placed in boiling water, with 

 amount of t ^ e O bj ect o f destroying the amylolytic ferment which 

 muscle 611 would effect the change. It is then taken out of the 



boiling water, reduced to a very fine state of division, 

 and boiled again in water. From this liquid, impure glycogen may 

 be precipitated by concentrating it and then adding an excess of 

 alcohol. The method of effecting the purification (by Briicke's 

 method) of the impure glycogen obtained by this method will be 

 described in connection with liver-glycogen. 



Abeles' method ^ * s excee dingly difficult, indeed almost impossible, 

 to extract the whole of the glycogen from muscles by 

 boiling them with water. Briicke 3 suggested that the muscle should 

 be boiled in a dilute solution of caustic potash. In this way the 

 whole of the glycogen is extracted, but a large quantity of proteid 

 matter passes into solution. Abeles 4 gets rid of this by boiling with 

 zinc chloride. His method is the following : 



1 Claude Bernard, Comptes Rendus, Vol. XLVIII. (1859) p. 673. 



2 Nasse, "Beitrage zur Physiologie der contractilen Substanz." Pfliiger's Archir, 

 Vol. ii. (1869) p. 97121. 



3 Briicke, Sitzungsber. d. Wien. Akad. Vol. LXIII. p. 214. 



4 Abeles, "Beitrage zur Kenntniss des Glycogens." Mcd. Jahrbiicher, 1877, p. 551. 



