No. I.] GIANT CELLS OF THE MARROW. 



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question, as I have no special observations of my own to offer 

 which might help to solve the problem. My own opinion has 

 been that this form of giant cell is produced by the fusion or 

 amalgamation of a number of smaller cells. I have been led 

 to this view chiefly from the fact, already mentioned, that they 

 seem to be found only when lying upon some solid substratum, 

 such as the septa of sponge or the spicules of spongy bone. 

 In the latter locality, when the spicules of forming bone are 

 covered with an epithelium of osteoblastic cells, it seems plaus- 

 ible to think that these closely packed cells might become 

 forced to form a polykaryocyte, and a number of apparently 

 transitional steps in this process can be seen in sections of the 

 femur in foetal cats about 9 cms. long. The rows of osteoblastic 

 cells are found in the same localities with the polykaryocytes, 

 and the nuclei of the cells have the same vesicular character in 

 both kinds of cells. As far, then, as my observations upon 

 this cell have gone, they have induced me to side with those 

 who believe they are derived from the fusion of small cells. 

 The function of these cells is unknown. The common view- 

 that they are concerned in the absorption of bone (osteoclasts) 

 seems to me to rest upon very slight evidence. If we find 

 them in developing bone lying upon the cartilage trabeculae 

 which are being absorbed, we find them also on the partitions 

 of sponge or pith, introduced into serous cavities where no 

 absorption is taking place ; and the conclusion in the first case 

 that the absorption which is going on is due to the giant cells 

 (osteoclasts) is illogical. Absorption of tissues is an occurrence 

 common enough in the body, and it is difficult to understand 

 why the absorption of bone or cartilage should require the 

 activity of a special cell, when the absorption of other tissues 

 does not. It would seem more probable that this form of cell 

 has no specific function, and that its formation is, in fact, acci- 

 dental or, in a certain sense, pathological : that the presence 

 of a solid substratum leads to an abnormally rapid growth of 

 lymphoid cells, leucocytes, osteoblasts, as the case may be, 

 and the fusion of some of these to produce multinucleated 

 giant cells. The same explanation might hold, as far as I can 

 see, to the occurrence of this form of cell in pathological for- 

 mations, except that in these cases the too rapid growth is 

 brought about by other conditions. 



