30 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



substance, which may present the greatest variety as to quantity. The 

 cell-membrane and so-called cell-capsule belong to these forms of proto- 

 plasmic modification. In cartilage and loose connective tissue this 

 intercellular substance exists in such amount that the still actively 

 moving protoplasmic cells appear to be forced apart by it. (See Fig. 24.) 

 Since the more active vital movements can only originate in the 

 semi-fluid protoplasm of cells, it is evident that the more or less rigid 

 intercellular substance could only take a slight part in organic processes 

 if there were not some means by which it could be brought into close 



FIG. 25. NERVE-FIBRES. (Thanhoffcr.) 



1, a, tnedullated nerve-fibre: b. non-medullated nerve-fibre from the sympathetic of the ox (after 

 Schultze) ; 2, non-medullated nerve-fibre from Jacobson's organ in the sheep (after Schnltze) ; 3, nerve- 

 fibres with Ranvier's nodes (R), from the sciatic of the frog: 4, funnel-shaped arrangement of medulla 

 from sciatic of frog, treated with osmic acid ; 5, nerve-fibre from frog, with axis-cylinder (t) and so-called 

 horny mesh-work; 6, diagram of medullated nerve-fibre: n, neurilemma; v, medullary sheath : t, axis- 

 cylinder. 



association with the active vital processes constantly occurring in the 

 interior of cells. Consequent!}' we find the entire intercellular substance 

 pierced of a mesh-work of fine canals, through which the cells send 

 prolongations of their outer layer, which, after numerous subdivisions, 

 serve to connect neighboring cells. 



By means of these juice-canals interchange between the contents of 

 the various cells is possible and the intercellular substance receives its 

 necessary supply of nourishment, while the connection of cell with cell 

 is an illustration of the loss of individuality of cell-life. Often we find 



