OBSERVATIONS UPON THE OCCURRENCE, 



STRUCTURE, AND FUNCTION OF THE 



GIANT CELLS OF THE MARROW. 



W. H. HOWELL, Ph.D., M.D., 



Professor of Physiology and Histology, University of Michigan. 



The observations which this communication is intended to 

 record were made in the course of a study of the hjematopoi- 

 etic function of the marrow, the results of which have been 

 given in the previous paper. The giant cells have been sup- 

 posed by some, notably by Foa and Salvioli (i), to have a 

 direct connection with the production of new red corpuscles ; 

 so that an investigation of this last subject necessitated a more 

 or less thorough consideration of the giant cells. My observa- 

 tion convinced me that no direct connection exists between the 

 giant cells and the newly formed red corpuscles. The reasons 

 upon which this conclusion is founded, together with certain 

 interesting facts not heretofore observed relating to these pe- 

 culiar cells, forms the excuse for the present brief paper, which 

 for the rest does not attempt to give any final solution to the 

 problem of their function in the marrow. My observations 

 have been confined to the cat, as this was the animal which 

 was found to be most convenient for the study of the blood 

 corpuscles. The giant cells, moreover, seem to show certain 

 differences in structure in different mammals (Werner), so that 

 by restricting the work to one animal the different preparations 

 could be more easily compared amongst themselves. 



Before attempting to give a description of these cells as 

 found in the cat's marrow, it is necessary to insist upon a 

 division of them into two classes, — a distinction which has 

 been emphasized before by certain writers, but which is for- 

 gotten or denied by others. We have, in the first place, giant 

 cells containing a variable number of separate nuclei. These 

 form what are generally described as giant cells or myelo- 

 plaques, and have been found not only in the marrow, but also 



