332 LESLIE B. AREY 



In working over this field and evaluating the total evidence the 

 writer has become highly skeptical concerning the potency of the 

 osteoblast in bone resorption. With Lewis ('13, p. 86) he would 

 take the position that 'There seems to be no satisfactory 

 evidence that the osteoclasts are the active causes of bone 

 destruction. On the contrary, they appear to be degenerating 

 cells, . . . ." 



Attention has been directed in another publication (Arey, '17 b) 

 to the uncritical nature of the assumption that the failure of a 

 cell to drink in vital dyes warrants the denying to it of phagocy- 

 tic potentiality. The' osteoclast refuses to 'stain' with trypan 

 blue (Shipley and Macklin, '16), yet bone cells, encapsulated or 

 naked, laid bare by the resorptive processes, are demonstrably 

 engulfed by it; 8 (compare also the observations of Wegner 9 and of 

 Rustizky ('14) on 'Kalkkorner' within polykaryocytes, and note 

 the red blood corpuscles within the body of the osteoclast shown 

 in figure 7 of the present communication.) Furthermore, the mere 

 presence of cytoplasmic inclusions within an osteoclast by no 

 means indicates that the latter was responsible for the dissolu- 

 tion of the material ingested; to imply such a causal relation is 

 to exceed the limits of legitimate deduction. When Jordan ('18, 

 p. 251) writes that "The osteolytic function of the giant-cells 

 of reticular and osteoblastic origin is proved by the presence of 

 globules of resorbed osseus substance [p. 262, globules of absorbed 

 bone] within the cytoplasm," he perhaps is using 'osteolytic' as 

 a term interchangeable with 'phagocytic;' this is supported by 

 a further reference (p. 255) to the ' ' 'phagocytic' (osteolytic) 

 function" of osteoclasts. Yet in another place (p. 246) we read: 



8 The presentation of these facts ('17 b) has led Meyer ('18 t p. 100) to conclude 

 that it involved "apparently implying that fusion products never observed to 

 undergo mitosis, nevertheless may be physiologically active and continue a pro- 

 gressive evolution." That these 1 giant -cells are active enough to engulf bone 

 cells, osteoblasts, or even fragments of bone matrix is unquestionably true, but 

 that the osteoclasts enjoy a progressive evolution is not supported by my obser- 

 vations. On the contrary, both in my 1918 communication and in the present 

 contribution the h'story of these elements is held to be one of advancing degen- 

 eration, culminating in death and removal. 



9 Cited by Rustizky (74). 



