NERVE-FIBERS. 



63 



from the adipose tissue which cannot be separated from the true 

 muscular tissue, fat is also a constituent part of muscle-plasma. 



The coloring-matter of the red muscle is myohematin, which is 

 probably produced from the hemoglobin of the blood. 



The inorganic salts are principally those of potassium, the most 

 abundant being potassium phosphate. 



Composition of the Cardiac Muscle. This variety of muscular 

 tissue contains paramyosinogen and myosinogen, and undergoes 

 cadaveric rigidity. 



Composition of Involuntary Muscular Tissue. Cadaveric rigidity 

 has been observed in the stomach and uterus ; and from plain 

 muscular tissue a proteid has been obtained which resembles 

 myosinogen. 



NERVOUS TISSUE. 



The nervous tissue of the body is made up of nerve-fibers, 

 nerve-cells, and neuroglia. 



Nerve-fibers (Fig. 58). This kind of nervous tissue is also 

 called fibrous and white nervous matter. 

 Fibrous nervous matter should not be 

 confounded with fibrous connective tis- 

 sue ; the term " fibrous" simply implies 

 that the nervous substance is arranged 

 in fibers. 



Nerve-fibers are medullated and non- 

 medullated. 



Medullated Nerve-fibers (Fig. 58) are 



Medullary 



sheath. 



- Fibrils of axial 



cord. 



- Neurilemma. 



- Segment of 



Lantermann. 



Axis-cylin- 

 der. 



FIG. 58. FIG. 59. 



FIG. 58. Longitudinal section through a nerve-fiber from the sciatic nerve of a 

 frog ; X 830 (Bohra and Davidoff ). 



FIG. 59. Medullate nerve-fiber from sciatic nerve of a frog; in two places the 

 medullary sheath has been pulled away by teasing, showing the "naked axis- 

 cylinder"; X212 (Bohm and Davidoff). 



