338 ALTEEATIOJ^ OF WEEVB FIBRES AND CAPILLARIES, &C. 



variations in vascular tension and blood distribution 

 wbicb occur in tlie healthy state through the agency 

 (if these nerves cannot take place. If, therefore, in 

 consequence of the body being exposed to very ad- 

 verse conditions the circulation be much disturbed, 

 the derangement cannot be compensatedor the injury 

 repaired. It too often happens, indeed, that the 

 damage progressively increases until sufficiently great 

 to render a fatal result inevitable. 



In fatty degeneration of the capillary vessels and 

 small arteries, the fine nerve fibres are also involved, 

 and the mechanism for regulating the flow of blood 

 through them is gradually impaired. In some cases 

 the nei've fibres and the muscular fibres of the arterial 

 coats have so completely degenerated that the distri- 

 bution of blood is greatly impeded. The outline of 

 the vessels becomes uneven, their coats thicker in 

 some places than in others, and the lining membrane 

 rough. The elasticity of the vascular walls is much 

 impaired, and in not a few instances the tube is 

 actually rigid. The nutrition of every organ in the 

 body suffers partly from changes which act through 

 the circulation of the blood, and in part from the 

 altered composition of the blood itself, which is 

 gradually induced by the deranged circulation oc- 

 curring in the blood-forming and blood-changing 

 organs. 



The changes in the minute vessels are, I believe, for 

 the most part brought about in this wise. From in- 

 creased nutrition the bioplasts of the capillary walls in- 

 crease in size and divide and subdivide. (See " Disease 

 Germs," 2nd edition, page 218,) Plate XXII, figs. 

 1, 2. Again, owing to the dilitation of the capil- 

 laries and thinning of their walls, particles of bio- 

 plasm escape from the blood and accumulate outside 

 the capillary wall. These grow and multiply, and 

 give rise to bioplasts from which connective tissue 

 may be formed, or which after a time may die, and 



