626 SPOEADIC DISEASES. 



in an artery. There being no arterial anastomosis in tiie lung, 

 such a plug has a very marked effect. The embolus cuts off the 

 normal supply of blood from the part, and the pressure in the 

 arterial branches beyond the stoppage falls to zero. The blood, 

 however, can still find its way through the capillaries into the 

 branches at the distal side of the plug. The branches of the 

 occluded artery are thus reduced to the condition of occluded 

 veins, and as they have none but capillary connections, they may 

 be said to form blind ends to the adjacent arteries. The blood then 

 trickles into these arterial branches and fills them, but no outward 

 flow can take place, therefore they become intensely engorged with 

 stagnant blood. Under these circumstances, the inner coat of 

 the vessel is deprived of its nutrition, for wliich the constant 

 renewal of the blood is required. This starvation of the minute 

 vessels renders them unfit for their function ; they lose their 

 power of retaining the blood, which escapes into the neighbour- 

 ing textures, forming the dense black consolidation now known 

 as hseraorrhagic impaction." 



SYMPTOMS. 



The symptoms of pulmonary apoplexy are very distressing. 

 The animal stands with outstretched legs, and seems to fight for 

 breath ; the nostrils will be seen opening and closing quickly, 

 the Hanks to heave rapidly ; the eyes are blood-shot and wild, or 

 sunken and dull ; there is a tremor all over the body ; the legs 

 and ears are deathly cold, and cold sweats bathe the body : the 

 pulse is small and indistinct (" the oppressed pulse of pneu- 

 monia" of the old writers), perhaps beating from 100 to 150 per 

 minute in extreme cases ; the heart's action tumultuous, but 

 without strength. 



In some cases there will be some discharge of frothy blood 

 from the nose ; in others haemoptysis is absent, and if the jugular 

 or other vein is opened, the blood trickles from it, black, thick, 

 and scanty. Death occurs by apnoea. ^ 



^ The term apncea is used by physiologists to indicate a condition of breathless - 

 ness induced by excess of oxygen [Handbook for the Physiological Laboratory, by 

 Sanderson and others, page 318), and by pathologists that of suffocation or asphyxia. 



