40 CHEMICAL PHYSIOLOGY. 



physiolysis or putrefaction commences. The muscle 

 yields the products common to the albuminous sub- 

 stances, tyrosine, leucine, volatile acids, and alkalies, 

 &c. The same products are obtained by chemolysis ; 

 leucine was first discovered (by Braconnot) in the 

 decomposed muscular tissue. By continuing the study 

 of chemolysis we shall probably be able to learn more 

 about the changes of the muscles in disease, as well as 

 about the ingredients of flesh extracts which are at 

 present unknown. 

 involuntary The smooth or organic involuntary muscular fibres 



muscles. 



contain some ingredients similar to those of the 

 striated, but require to be better studied a matter of 

 great difficulty, as they cannot easily be isolated. 

 ingredients The nerves and brain consist mainly of minutely 

 fafo \ on g fibres, and of cells standing in connection 

 with these fibres. These fibres are membranous tubes, 

 filled with a peculiar nerve or brain marrow. When 

 the nerves are taken out of the living body they change 

 quickly, and the marrow of the tubes separates into 

 two substances a central one, the cylinder axis, and 

 an outer or periaxial portion. This change is not yet 

 quite explained. Possibly it may consist in a coagula- 

 tion of the axial cylinder, which causes its contraction. 

 The axial cylinder is, however, already in life of a 

 different chemical composition from the periaxial tube, 

 for it shows no effects in the polariscope, while the 

 periaxial part exhibits dark or light crosses. The 

 chemical constitution of these matters is perhaps the 

 greatest problem of organic and physiological chemistry. 

 A consideration of all researches since the time of 



of the brain 



and nerves. 



