406 PATHOLOGY AND TREATMENT OF SHOCK AND SYNCOPE. 



instances with the reduction of the blood-pressure and the in- 

 duction of syncope. As the skin is usually pallid during the 

 fainting fit itself, we can hardly suppose that the blood is 

 then flowing very rapidly through the cutaneous vessels. 

 If the hypothesis I have just advanced be correct, we are 

 driven to the conclusion that it is the blood-vessels of the 

 muscles which undergo dilatation during syncope. This idea 

 likewise receives confirmation from the observation made by 

 Thackrah,* that it is in muscular men that venous blood most 

 irequently presents a florid colour. Such of you as have seen a 

 living muscle cut across, however, know that when it is at rest 

 very little blood indeed flows from the divided ends of the 

 vessels which permeate its substance, and you may be inclined 

 to doubt the possibility of these vessels ever being able to dilate 

 so much as to drain, as it were, the blood from the arteries into 

 the veins and produce syncope. That they can dilate and drain 

 the blood out of the arteries very quickly has been shown by 

 Ludwig and Hafiz,t who found that when the vessels of the 

 "intestines and skin were made to contract, the blood which 

 ■could no longer flow through them poured through the vessels 

 ■of the muscles, and, notwithstanding the fact that these vessels 

 were at that very time excited to contraction by irritation of 

 their vaso- motor nerves, the blood flowed from the arteries into 

 the veins, and the pressure in the arteries sank nearly as quickly 

 as when the cutaneous and intestinal vessels were patent. If 

 such be the effect of the muscular arteries on the blood-pressure 

 when they are trying to contract, what must it be when they are 

 ready to dilate ? Dilatation of the vessels alone may sometimes 

 be sufficient of itself to lower the blood-pressure to such an 

 extent that fainting occurs ; but at other times this is combined 

 with the depressing effect of sudden stoppage of the heart. In 

 shock there is great dilatation of the vessels in the interior of 

 the body, especially of the veins of the intestine. If this state 

 should be associated with sudden stoppage of the heart, instant 

 death will occur, as in the case of the labourer in the India 

 Docks. In short, then, I consider syncope to depend chiefly on 



* Thackrah, Inquiry into the Nature and Froverties of the Blood, p. 85. 

 f Lvdwig's Arbeiten, 1871, p. 107. 



