GENERAL PROPERTIES! THE CORPUSCLES. 403 



a short time at very high altitudes (4000 meters) causes a marked in- 

 crease in the number of red corpuscles, an increase, for instance, 

 from 5,000,000 per c.mm. to 7,000,000 or even 8,000,000. This fact 

 has since been investigated with great care by a large number of 

 observers and under a great variety of conditions. The observation 

 has been abundantly confirmed, and indeed it would seem that the 

 reaction takes place very quickly. Within twenty-four hours, 

 according to some observers, and in less time, according to others 

 who have experimented during balloon ascensions (Gaule, Hallion, 

 and Tissot), the increase in the number of corpuscles may be de- 

 tected, although the maximum increase comes on more gradually. 

 According to Kemp,* the number of blood plates is also greatly 

 increased by high altitudes, while the leucocytes are not affected. 

 There has, however, been much difference of opinion as to whether 

 this increase in number of the red corpuscles is relative or absolute, 

 that is, whether the total number of red corpuscles in the blood, 

 and therefore probably the total amount of hemoglobin, is increased, 

 or whether it is simply an apparent increase due, for instance, to a 

 diminution in the water of the blood and a consequent concentration 

 as regards the number of corpuscles. The results published upon 

 these questions are so conflicting that it is difficult to make any 

 positive statements at present. One may, however, believe that 

 the increased number or concentration of red corpuscles is an adap- 

 tation by means of which the oxygen-carrying capacity of the blood 

 is raised to compensate for the diminished amount of oxygen in the 

 air. According to one set of observers, this adaptation is brought 

 about by an actual that is, an absolute increase in the total 

 number of red corpuscles, and therefore in the total amount of 

 hemoglobin. According to this explanation, one must assume fhat 

 the diminished amount of oxygen in the air at high altitudes or 

 some other condition peculiar to these altitudes acts as a stimulus 

 to the blood-forming tissues (red marrow) and augments the output 

 of corpuscles. According to another set of observers, the adap- 

 tation is brought about by a concentration of the blood. The blood- 

 plasma is reduced in quantity, perhaps by transudation of water 

 into the tissues, and therefore the number of red corpuscles and the 

 amount of hemoglobin become greater for each cubic millimeter. 

 If we assume that this smaller bulk of blood, more concentrated 

 in corpuscles and hemoglobin, circulates more rapidly, then also 

 the oxygen-carrying capacity of the blood is increased. Recent 

 evidence seem to favor this latter explanation, particularly as 

 regards the nearly immediate effects of a change in altitude. 

 Abderhalden, for instance, has shown that, if animals of the 

 same species and same litter are bled to death and the total 

 * Kemp, "American Journal of Physiology," 10, 34, 1904. 



