100 PATHOLOGY. 



from any of tlie causes already enumerated. When caused by 

 direct pressure, the coagulation commences at the point where 

 the obstructing cause comes into contact with the vessel, and 

 extends as far as the collateral branches ; when from debility, 

 diminished cardiac power, or gravitation, the coagulation com- 

 mences first behind the flaps of the valves, and appears to be 

 owing to the force of the current being insufficient to completely 

 open the valves. The blood thus allowed to lodge and stagnate 

 coagulates and forms a thrombus or clot, which may finally 

 obstruct the whole venous channel as far as the next large 

 collateral branch. 



Treatment of congestion. — Tlie most important means for the 

 removal of congestion are those which tend to remove its cause ; 

 and if the causes already enumerated are borne in mind, the 

 practitioner will at least have some guide to the proper line of 

 treatment. When the congestion is due to the influence of cold 

 upon the surface, clearly the first step is to restore the circulation 

 of the skin by warmth, friction, and by the administration of 

 remedies, such as the spirits of nitrous ether, which are known 

 to promote diaphoresis. If the congestion be due to diminished 

 cardiac power, or debility of the vessels — and this is often induced 

 by watit of exercise — the lost power and tone must be restored 

 by good food, pure air, regular and moderate exercise, and tonics. 

 If the debility of the vessels be very great and obstinate, 

 the effects of ergotine may be tried. This remedy acts by 

 producing contraction of the blood-vessels ; it may be very 

 conveniently used hypodermically. The effects of bandaging, in 

 supporting the weakened vessels of congested limbs, should 

 not be lost sight of, nor its a]:)plication neglected. In many 

 instances a watery condition of the blood is associated with 

 debility of the circulatory apparatus : in such cases tonic remedies 

 combined with diuretics act most favourably. 



In severe internal congestions, where not only the organ chiefly 

 affected is filled with blood, but the right side of the heart and 

 the great veins also, the necessity of affording mechanical relief 

 becomes a serious question, and very often an urgent necessity. 

 It is very true that severe internal congestions, more especially 

 those of the lungs and brain, are generally associated with 

 greatly diminished cardiac power, feeble pulse, and nervous pro- 

 stration; and if we were to admit what is so commonly in- 



