404 BLOOD AND LYMPH. 



quantity of hemoglobin is estimated, the average figures obtained 

 for the animals at low levels are the same as for those at the 

 high altitudes.* 



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 can not be said that we possess any 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 system used by most authors is that 

 adopted by Ehrlich.f According to this nomenclature, the white 

 corpuscles fall into two main groups, the lymphocytes and the 

 leucocytes, and each of these into two or more subgroups. Thus: 



I. LYMPHOCYTES. No granules in the cell substance, and, though capable of 

 ameboid changes of form, this property is not characteristic and prob- 

 ably not sufficient to cause locomotion. 



(a) Small lymphocytes are about the size of the red corpuscles; the nu- 

 cleus is large, symmetrically placed, stains homogeneously, and the 

 cytoplasm is reduced to a very small amount. They form from 20 

 to 25 per cent, of all the white corpuscles. 



(6) Large lymphocytes. Two to three times as large as the preceding. 

 Nucleus somewhat eccentric; the cytoplasm is relatively more 

 abundant than in a, but non-granular. These forms exist only in 

 small numbers, forming 1 per cent, or less of the white corpuscles. 

 II. LEUCOCYTES. Granules of different sorts found in the cytoplasm. Cells 

 characteristically ameboid. 



(a) Transition forms (uninuclear leucocytes). Single largr nucleus, more 

 or less lobulated; cytoplasm abundant and faintly granulated. The 

 granules stain with neutral dyes and are therefore designated as 

 neutrophile granules. The name, transition form, implies that these 

 leucocytes represent an intermediate stage between the large lympho- 

 cytes and the following variety. This form exists in small numbers, 

 2 to 10 per cent, of the total number of white corpuscles. 



(b) Polynuclear or polymorphonuclear leucocytes. The nucleus is seg- 



mented into lobes connected by narrow strands. The cytoplasm 

 is especially ameboid and is granular. The granules in most cases 

 are neutrophilic and small in size. The typical cells of this kind 

 form the bulk of the white corpuscles of the blood, 60 to 75 per 

 cent. Eosinophilic leucocytes form a subgroup of this variety. They 

 have a similar segmented nucleus, but the cytoplasm contains nu- 

 merous coarse granules that stain in acid dyes, such as eosin, whence 

 the name. 



(c) Mast cells. These peculiar cells exist in very small numbers under 



normal conditions, less than 1 per cent, of the total number of 



* For the extensive literature see Van Voornveld, "Das Blut im Hoch- 

 gebirge," "Pfliiger's Archiv," 92, 1, 1902; also Oliver, "A Contribution to the 

 Study of Blood and Blood Pressure," London, 1901. 



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

 Physiologic," 3, part i, 1904. 



