302 WOUNDS AND THEIR TREATMENT. 



ored, blood flows out of the wound. Hemorrhages in small and 

 medium-sized veins generally stop without any surgical interfer- 

 ence, but the large veins, especially those in the neighborhood of 

 the heart, are dangerous and should be taken up quickly. Capillary 

 bleeding consists in a slow trickling of blood, which, as a rule, 

 lasts for a very short time and is of no great importance. 



A serious hemorrhage endangers the animal's life, and the more 

 rapid it is the greater the danger. The following symptoms are 

 presented: general coldness of the skin and extremities; paleness 

 of the mucous membranes, especially the mouth and eye ; great 

 prostration ; staggering gait ; and often from weakness inability 

 to rise. In some cases we have unconsciousness, dyspnoea, enlarge- 

 ment of the pupils, uncontrollable evacuation of urine and feces, 

 finally slight convulsions, and death. This conclusion is to be 

 expected if about half the blood contained in the body is lost in a 

 very short time. 



Many experiments have been made upon the dog in order to find 

 what are the consequences of slight hemorrhages. One-fourth of a 

 dog's blood may be withdrawn without causing any appreciable les- 

 sening of the blood-pressure in the arteries. The pulse may become 

 very indistinct while the blood is withdrawn, but it is soon restored 

 to its ordinary pressure if the hemorrhage is stopped, from the fact 

 that the arteries contract in proportion to the smaller quantity of 

 blood. The rapidity of the current and the number of contrac- 

 tions of the heart remain the same as before the hemorrhage. Any 

 loss of blood amounting to more than one-third of the blood-mass 

 reduces the blood-pressure very much. The current becomes slow 

 and contractions of the heart are much less. At the same time 

 the composition of the blood is changed. At first we observe a 

 compensation of the water of the blood, and the salts which are 

 thereby being reabsorbed from the tissues when this is exhausted; 

 then albumin is drawn into the blood. It requires a much longer 

 time to form new blood-cells after the animal has been bled of 

 one-fourth of the weight of the body. The red blood-corpuscles 

 become normal and return to their original number in from seven 

 to thirty-four days. 



The hemorrhage is stopped by the closing of the bloodvessel by 

 a clot or thrombus. The blood within the walls of the bloodvessels 

 is only kept in a liquid condition as a result of its contact with 



