388 THE AMERICAN MONTHLY [Nov. 



to some histologists. First, and this quite often, the 

 mast-cell is surrounded by irregularly scattered granules 

 which resemble the granules of mast-cells. These may 

 be considered free mucin, which will be taken up by the 

 mast-cells, or has been shed by them. I consider the 

 latter opinion the correct one. In a carcinoma I once 

 found the connective tissue in parts thickly studded with 

 mast-cell granules. 



The second variety requires neutral decolorization, and 

 is therefore not so well known. In this variety individual 

 mast-cells are surrounded by a homogeneous substance, 

 which manifests the reaction of the mast-cell granules, but 

 contains no granules. In these we are dealing with 

 either a mucin meta-morphosis of the intercellular sub- 

 stance, or with the "shell-plates" described above, though 

 not easily identified as such. This variety I have found 

 most often in fresh scar tissue. 



Thirdly, by neutral decolorization, in a variety of skin 

 diseases, mast-cells can be demonstrated which present 

 the usual form, but are peculiar in this respect, that they 

 show the usual granulation only at one pole, or arranged 

 laterally, instead of around the nucleus. The rest of the 

 cell-body is constructed like that of an ordinary spindle- 

 shaped connective tissue cell. I consider this variety to 

 be mast-cells in process of development. 



Fourthly, by the same process of decolorization mast- 

 cells can be demonstrated which present the usual form, 

 but distinguished by the spongioplasm containing the 

 granules, which assumes the same diffused red stain as 

 the latter. The cells are to be considered either as mast- 

 cells supersaturated with mucin, or as such in which the 

 mast-cell granulation has become liquefied and dissolved. 



Of these four rarer forms, which are, however, often 

 met with by proper staining methods the second and 

 fourth, as is seen, bear some relation to the fifth variety 

 herein described and known as the ''mast-cell with shell- 



