THE MAST CELLS 



and its appendages together with a layer of dermis whose thickness varies from 

 one species to another. These preparations were then compared with paraffin 

 sections of whole-thickness skin to determine the level at which the separation 

 had been made. Mast cells were counted as before in the inner and outer zones 



\* 





^s 



V. 



•'--- ~ 



-iHarfc ■ 



Fig. 58 



Mouse skin. Staining and magnification as in Fig. 57. The mast 

 cells in the skin of the mouse are disposed in two layers, inner and 

 outer, and are mainly big cells (see also Fig. 61). Splitting the skin 

 at the level of the arrows results in an almost equal division both of 

 mast cells and histamine. 



of the sections of intact skin, corresponding values for histamine being obtained 

 from samples of the separated inner and outer layers. The results are set out 

 in Table XXV. 



Results. Again there is a striking parallelism between the mast-cell content 

 and the histamine value in the various layers of skin in every species examined. 

 This is particularly evident in those animals in which the skin histamine is 



148 



