CHAPTER X. 



PHLEBOTOMY, SCARIEICATION, AND TRANSEUSION. 



By phlebotoni}' is meant the surgical openincr of a vein for the 

 purpose of removing blood. Although bleeding is almost invariably 

 practised on veins, arteries may be utilised for the same purpose, and 

 the old term blood-letting included venesection or phlebotomy and 

 arteriotoni}-. Bleeding from capillary vessels is usually effected by 

 scarification or the application of leeches. 



Bleeding may be divided into general and local. General bleeding 

 consists in removing a large volume of blood with the object of 

 lowering blood-pressure throughout the body ; local bleeding, on the 

 other hand, is undertaken to reduce the quantity of blood in the part 

 operated on or in its immediate vicinity, i. e. to improve the conditions 

 in a circumscribed area. 



Bleeding from arteries and capillaries is much less commonly 

 performed than from veins, and venesection, formerly practised in the 

 most widely differing localities, tends to become more and more 

 confined to the jugular vein. In former times bleeding was popular 

 in all acute and feverish conditions, and was so excessively prac- 

 tised that a reaction naturally set in. It has now almost fallen 

 into desuetude, a result accelerated and confirmed by the entirely 

 different views now held as to the value of general bleeding. In 

 bacteriological laboratories, of course, bleeding is a necessary pre- 

 liminary to the preparation of protective sera, and is also resorted to 

 for obtaining blood for microscopical or bacteriological experiments. 

 The periodical bleeding of animals in spring to keep them in good 

 health is still practised in a few parts of the country, but is rapidly 



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