332 



CIRCULATION OF NUTRITIVE FLUID. 



else than the minutest subdivisions of the veins and arteries, which 

 commonly inosculate freely with each other. 



590. The degree of this inosculation, and the consequent form of the 

 capillary network, are subject, however, to very great variations ; and 

 these may be generally shown to have a relation to the form of the 

 ultimate elements of the tissues, which are traversed by the capillaries. 

 Thus we have seen in the capillaries of Muscle, that the major part run 

 parallel to the course of the fibres, lying in the minute interspaces be- 

 tween them (Fig. 67); a few transverse branches serving to connect 

 them with each other. A similar distribution prevails in the capillaries 

 of the Nervous trunks ; but those of the Nervous centres are arranged 

 in the form of a minute network, so as completely to traverse every 

 part of the structure (Fig. 93). Again, we observe that the capillaries 

 of Glands form a minute network around the secreting follicle (Fig. 

 94) ; and a similar arrangement prevails in the capillaries of the air- 

 cells of the lungs, which are set so closely together, that it would seem 



Fig. 93. 



Fig. 94. 



Capillary Network of Nervous Centres. 



Capillary Network around the follicles of 

 Parotid Gland. 



as if the purpose were to cover the surface with blood as completely as 

 possible, consistently with its being retained within vessels, and not 

 spread out into a continuous film (Fig. 106). A network of very much 

 the same character is found in the villi of the mucous membrane (Fig. 



Fig. 95. 



Fig. 96. 



Capillary Network in simple mucous mem- 

 brane of palpebral conjunctiva. 



Capillary Network in choroid coat of 

 the eye. 



82), on the ordinary surface of simple mucous membrane (Fig. 95), and 

 on that of the choroid coat of the eye (Fig. 96). Where the surface of 

 the mucous membrane is depressed into follicles, the arrangement of the 



