THE BLOOD. 



237 



that the bell shape can not be due to the action of the fixatives employed in 

 the preparation of the tissues. 



The structure of the corpuscle, according to Weidenreich, differs also 

 from that usually stated. He asserts that the corpuscle is surrounded by a 

 structureless, colorless membrane enclosing a colored but not nucleated 

 semi-fluid mass, which consists chemically of protein material, lecithin, 

 cholesterin, inorganic salts and hemoglo- 

 bin. There is no evidence of the existence 

 of a stroma in the adult state. 



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 milli- 

 meter of blood by various observers em- 

 ploying different methods with compara- 

 tively uniform results. The average normal 

 number of corpuscles in one cubic milli- 

 meter 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 physio- 

 logic 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., co- 

 pious 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 apparently 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: 



FIG. roc. RED CORPUSCLES 

 SKETCHED WHILE CIRCULATING IN 

 THE VESSELS OF THE OMENTUM or A 

 GUINEA-PIG. (F. T. Lewis in Stohr's 

 Histology.} 



This increase in the number of corpuscles takes place, according to 

 Viault's observations, within two or three weeks, and is apparently not con- 



