BLOOD AND H^EMOPOIETIC ORGANS 81 



as it may be when various pathological agents are at 

 work, so much solid bile matter is formed that the 

 resulting viscidity of the bile may block the passages, 

 and hsematogenous jaundice result (see p. 283). 



The destruction of haemoglobin would appear to take 

 place to some extent independently of the red corpuscles 

 as a whole, It has been found, for example, that the 

 amount of it falls by about 7 per cent, during the day, as 

 a result, presumably, of the wear and tear of life, and 

 rises about the same amount during the night.'* 



In persons who work by night this alternation is 

 reversed, whilst exercise increases the daily fall. In 

 these observations the number of corpuscles was not 

 affected ; the variation is in the * worth ' of each cell. 

 This helps to explain the undoubted aid which rest in 

 bed affords in the building-up of blood in anaemic 

 subjects. 



White Cells. Ever since the publication of Virchow's 

 ' Cellular Pathology,' the white cells, which make up the 

 second great tribe in the population of the blood-stream, 

 have been objects of the greatest interest to pathologists, 

 and in recent years have had devoted to them a greater 

 amount of research and a larger literature than any 

 other single set of cells in the body. Unfortunately, 

 however, many important points as to their origin and 

 life-history are still shrouded in obscurity. Unlike the 

 red corpuscles, the white cells are not all of one sort. 

 They differ in size, in the character of their nuclei, in 

 the staining reactions of their protoplasm, and in the 

 presence or absence of granules in the cell body, and 

 * Edgecombe, Brit. Med. Journ., 1898, i. 1650. 



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