GENERAL PROPERTIES: THE CORPUSCLES. 439 



the quantity' of hemoglobin is given in Fig. 185, a. It has been 

 assumed that this effect of altitude is due directly to the lowered 

 pressure of oxygen and that the reaction is an instance of physio- 

 logical adaptation. As the pressure of oxygen falls in the sur- 

 rounding air and the supply of oxygen to the body becomes im- 

 periled, compensation is effected by the increased activity of the 

 red marrow sending out more corpuscles to act as carriers of the 

 oxygen. That oxygen lack or fall in oxygen tension is an effective 

 stimulus to the blood-forming tissue in the marrow has been 

 demonstrated by laboratory experiments upon animals.* The full 

 increase in the number of red corpuscles in the case of individuals 

 transferred from a low to a high altitude does not occur immedi- 

 ately. There is a rapid increase in hemoglobin and in the number 

 of red corpuscles during the first two or three days, followed by a 

 more gradual increase extending over several weeks. This reaction 

 contributes the most important feature of the process of acclimati- 

 zation. In the course of the numerous investigations made upon 

 this subject t some observers have reported that in sudden changes 

 of altitude there may be observed an immediate increase in the 

 number of red corpuscles, too rapid to be explained by an aug- 

 mented functional activity of the marrow. Effects of this kind 

 when they occur are to be explained doubtless by some immediate 

 reaction to the changed physical conditions, such, for example, as 

 the emptying of stagnant capillary areas, or a concentration of the 

 blood-plasma due to passage of water from the blood into the 

 tissues. 



Physiology of the Blood Leucocytes. — The function of the 

 blood leucocytes has been the subject of numerous investigations, 

 particularly in connection with the pathology of blood diseases. 

 Although many hypotheses have been made as the result of this 

 work, it cannot be said that we possess much positive information as 

 to the normal function of these cells in the body. It must be borne 

 in mind, in the first place, that the blood leucocytes are not all the 

 same histologically, and it may be that their functions are as diverse 

 as their morphology. Various classifications have been made, 

 based upon one or another difference in microscopical structure and 

 reaction, but at present the terminology most used in medical 

 hterature is that adopted by EhrHch. f According to this nomen- 

 clature, the white corpuscles fall into two main groups — the 



* Dallwig, Kolls and Loevenhart, "American Journal of Physiology," 39, 

 77, 1915. 



t For the extensive literature consult Zuntz et al, "Hohenklima und 

 Bergwanderungen in ihrer Wirkung auf den Menschen," 1906, and Douglas et 

 al, "Philosophical Transactions Royal Society of London," B, vol. 203, p. 18.5, 

 1913. 



t Ehrlich, "Die Anaemie," 1898; see also Seemann, "Ergebnisse der 

 Physiologie," 3, part i, 1904. 



