PLATE XXI —MECHANISM GOVERNING THE DISTRIBUTION OF 

 BLOOD IN THE CAPILLARIES. 



Diagram to show self-regalating roeclianisin connected "with, the minute arteries and 

 capillaries, a, artery -with muscular fibre cells ; the dark lines show its diameter -when 

 dilated. 6, gmallvein. c, capillary net'work. Over No. 1 the capillaries axe dilated, 

 and over No. 2 they are contracted, d is a ganglion cell with at least two sets of nerve 

 flhres connected with it, one of vrhich, e, divides and subdivides, giving off nerve-fibres 

 ■which are distributed to the artery a, while the other,/, is continuous vnth the plexus 

 of nerve fibres ramifying close to the capillary vessels. Nerve fibres are also dis- 

 tributed to the small vein, ft, but these are not represented in the drawing. The bio- 

 plasm of the vessels and nerve-fibres is shown, p. 327, 



[329 



