POPULAR ERRORS. 85 



circulation of the blood was discovered by Harvey, and is still a 

 favorite dogma with mankind. The error itself in regard to any 

 local or limited impurity or stagnation of the blood, is contradicted by 

 the fact that the blood, which is seen to be black, is often so when 

 taken from a part confessedly free from all disease, and where leeches 

 have been applied only to relieve some distant part. Besides, the 

 blood so drawn and esteemed to be impure, was a few seconds before 

 mingling with, and forming an integral part of the circulating mass, 

 and had passed along the great vessels from the heart. If the blood, 

 therefore, is black from impurity, it is so in common with all the 

 blood of the body, and this at a [time when the general health is 

 unimpaired. The truth of the matter is that the blackness is in a mea- 

 sure accidental, and depends upon the time at which the leeches dis» 

 gorge their blood, and the depth of the wound they make to extract 

 it. In the opinion of the nurse, and too often of intelligent friends, the 

 appearance of the blood forms a material part of the report to be 

 made of the patient to the physician ; and as might be expected, 

 instances occur, where, from the influence of this pi-ejudice, a repeti- 

 tion of the leeching is improperly resisted, or improperly desired, and 

 the bitterness of the bereavement of some beloved object is sometimes 

 aggravated by secret reflections gi'ounded on this error, as to the 

 benefit which a repetition of the leeching might have conferred, or 

 the injury its repetition had inflicted. 



But besides the popular error, just noticed, of impurity of blood as 

 forming a constituent part of disease, and affording by its colour the 

 evidence of it, there is another popular error relating to the blood, 

 and something allied to it, and which has been bequeathed to us by 

 those, who viewing the body as a machine, regarding all the sevei*al 

 functions of it to be subject to the laws of mechanics. Among the 

 errors derived from this source, and which have descended to us, and are 

 still generally entertained, is that of the greater tendency of persons to 

 become affected with apoplexy, who have what are called short necks ; 

 this tendency being caused, it is said, by the greater force which the 

 heart is thereby enabled to exert upon the shorter column of blood in 

 short necked persons, agreeably to a well-known law of hydrostatics. 



But a fundamental objection to this assumption, and, therefore, one 

 that is fatal to it, is that there is no truth in the notion that that part 

 of the vertebral column forming the neck, differs in length in any 



