238 



TEXT-BOOK OF PHYSIOLOGY. 



Number of Red Corpuscles. In any given specimen of blood 

 the corpuscles are so numerous and the spaces between them so 

 small that it seems almost impossible to determine their number. 

 This, however, has been accomplished for a cubic millimeter of 

 blood by various observers employing different methods with compara- 

 tively uniform results^ The average normal number of corpuscles in 

 one., cubic millimeter of blood is, for men, 5,000,000; and for women, 

 4, 500,000^, This value, however, will vary within slight limits, with 

 variations in the activity of physiologic processes and to a large extent 

 at times in pathologic states of the blood or body. The number is 

 increased in the cutaneous veins by all influences which cause a 

 diminution in the quantity of water in the blood e. g., copious 

 sweating, acute watery diarrhea, fasting, abstinence from liquids; 

 the number is diminished by influences which dilute the blood e. g., 

 the ingestion of liquids, the absorption of fluids from the tissue spaces, 

 etc. But it is well to remember that these influences which produce 

 changes in the number of corpuscles per cubic millimeter do not 

 necessarily produce corresponding changes in the total number of 

 red corpuscles in the body. In women lactation, menstruation, and 

 the act of parturition diminish the number. High altitudes appar- 

 ently increase the number of corpuscles, as shown by their increase in 

 the blood of the peripheral vessels. Whether this is an indication 

 that there is a corresponding increase of the total number in the 

 general volume of the blood is uncertain. The following table will 

 show the increase in the count per cubic millimeter at different 

 altitudes: 



This increase in the number of corpuscles takes place, according 

 to Viault's observations, within two or three weeks, and is apparently 

 not connected with either diet or mode of life, but rather with dimin- 

 ished atmospheric, if not oxygen, pressure. On returning to sea- 

 level there is a gradual reduction, without any apparent destruction 

 of the corpuscles, to their normal number. The reason for these 

 variations is not clear. 



The method of counting corpuscles introduced by Vierordt and 



