COAGULATION OF THE BLOOD IN THE ORGANISM. 27 



reported a case of death by lightning where a loose coagulum was found in the heart 

 twenty-four hours after. In this case, decomposition was very far advanced, and it is 

 probable that the coagulura had become less firm from that cause. His observations also 

 show that coagulation occurs after poisoning by hydrocyanic acid, and in animals hunted 

 to death. 



Coagulation in different parts of the vascular system is by no means unusual during 

 life. In the heart, we sometimes find coagula which bear evidence of having existed for 

 some time before death. These were called polypi by some of the older writers, and are 

 often formed of fibrin almost free from red corpuscles. They generally occur when death 

 is very gradual and when the circulation continues for some time with greatly-diminished 

 activity. It is probable that a small coagulum is first formed, from which the corpuscles 

 are washed away by the current of blood ; that this becomes larger by farther depositions, 

 until we have large, vermicular masses of fibrin, attached, in some instances, to the 

 chordee tendineee. Clots produced in this way may be distinguished from those formed 

 after death by their whitish color, dense consistence, and the closeness with which they 

 adhere to the walls of the heart. 



Bodies projecting into the caliber of a blood-vessel soon become coated with a layer 

 of fibrin. Eough concretions about the orifices of the heart frequently induce the deposi- 

 tion of little masses of fibrin, which sometimes become detached and are carried to vari- 

 ous parts of the circulatory system, as the lungs or brain, plugging up one or more of the 

 smaller vessels. The experiment has been made of passing a thread through a small 

 artery, allowing it to remain for a few hours, when it is found coated with a layer of 

 coagulated fibrin. 



Blood generally coagulates when effused into the areolar tissue or into any of the 

 cavities of the body ; although, effused into the serous cavities, the tunica vaginalis for 

 example, it has been known to remain fluid for days and even weeks, and coagulate when 

 let out by an incision. In the Graafian follicles, after the discharge of the ovum, we 

 sometimes have the cavity filled with blood, which forms a clot and is slowly removed 

 by absorption. 



Coagulation thus takes place in the vessels as the result of stasis or of very great retarda- 

 tion of the circulation, and in the tissues or cavities of the body, whenever it is accident- 

 ally effused. In the latter case, it is generally removed in the course of time by absorp- 

 tion. This takes place in the following way : First, we have disappearance of the red 

 corpuscles, or decoloration of the clot, and the fibrin is then the only substance which 

 remains. This becomes reduced from afibrillated to a granular condition, softens, finally 

 becomes amorphous, and is absorbed ; although, when the size of the clot is considerable, 

 this may occupy weeks, and even months, and may never be completely effected. Effused 

 in this manner, the constituents of the blood act as foreign bodies ; the corpuscles cease 

 to be organized anatomical elements capable of self-regeneration, break down, and are 

 absorbed. The fibrin which remains undergoes the same process, the stages through 

 which it passes being always those of decay, and not of development. In other words, 

 the clot is incapable of organization. 



Office of the Coagulation of the Blood in arresting Hcemorrhage. The property of the 

 blood under consideration has a most important office in the arrest of haemorrhage. The 

 effect of an absence or great diminution of the coagulability of the circulating fluid is 

 exemplified in instances of what is called the haamorrhagic diathesis; a condition in which 

 slight wounds are apt to be followed by alarming, and it may be fatal hemorrhage. This 

 condition of the blood is not characterized by any peculiar symptoms except the obsti- 

 nate flow of blood from slight wounds; and this may continue for years. In a case 

 which came under our observation a few years since, excision of the tonsils was 1<>1- 

 lowed by bleeding, which continued for several days, and was arrested with great dif- 

 ficulty. On inquiry it was ascertained that the patient, a young man about twenty 



