The Physiological Destruction of Erythrocytes in Birds. 549 



hemophages are confined to the intima of the venons capillaries, while 

 the intima of the larger vessels displays no such phagocytic action 

 (Fig. 1, a and b). The contrast in this regard is distinct and under 

 normal conditions therefore it appears that the hemophages are actively 

 phagocytic cells of a specialized intimai endothelium, differing in degree 

 at least in this regard from vascular endothelium in general. This 

 is not denying of course a potential phagocytic power possessed by 

 endothelium in general which may be provoked under abnormal 

 conditions l ). 



I have observed no evidence that physiologically the hemophages 

 are at any time other than fixed-tissue cells. I have not seen them 

 free in the lumen of the larger vessels although present in such great 

 numbers in contributing capillaries. This fact militates against the 

 suggestion of Metchnikoff that these cells are leucocytes which have 

 been transported to the liver. This suggestion is also met by the fact 

 that the hemophages are definitely attached to the vessel-wall and 

 localized in a given type of vessel. 



From the point of view of general physiology it is of' course 

 important to determine whether or not the action of the hemophages 

 is peculiar to birds or is a widely occurring phenomenon. The latter 

 is the case. In applying the same technique in a study of the livers 

 of the frog (Rana pipiens), toad (Bufo lentiginosus), turtle (Chrysemys 

 marginatus), crocodile (Alligator mississipiensis), and opossum (Didel- 

 phys virginiana), I have found a similar cycle of intracellular blood 





*) The descriptions in this paper are limited to strictly normal conditions. 

 The behavior of the hemophages under modified conditions, I shall discuss in a 

 later paper. It may be staded in this connection however, that by the injection 

 of foreign bodies or colloilal solutions, the phagocytic activity of the hemophages 

 may be enormously increased. This applies both as to the action of a given cell 

 and as to the number of cells participating. This phagocytic activity leads not 

 only to the ingestion of the injected material, but to an increased ingestion of red 

 blood-corpuscles from the circulating blood. Foreign erythrocytes injected into the 

 blood-stream are rapidly taken up and digested by the hemophages. The same is 

 true of certain bacteria. In both instances the large amount of anti-body contai- 

 ned in the liver after such procedure, indicates that the hemophages are definitely 

 concerned in anti-body production. I have evidence also that colloids in general 

 are ingested by the hemophages and in my opinion much of the so-called vital stai- 

 ning of these cells is essentially a phagocytosis of colloidal pigments. (Cf. Evans. ) 



