48 ON DIFFERENTIAL REACTIONS TO VITAL DYES, ETC. 



Tschaschin's claim, in his experimental study of peritonitis, for the feasibility of 

 identifying mesol helium by means of the vital stain, finds the fullest corroboration 

 in our experiments. We can not help but feel that decided support is thereby given 

 to the belief that the mesothelial elements constitute a distinct cell strain sui 

 generis and in the case of injury must repair themselves. 



SUMMARY. 



4. The two great cell strains of the connective tissue of mammals — the fibro- 

 blasts and the macrophages — exhibit a pronounced and characteristic difference in 

 their reaction to intra-vitam acid dyes. 



2. This difference shows itself in the appearance of two sharply separated types 

 of response to the d} r e — in the size, form, and number of the vital dye "granules" 

 and in the fact that these types of vital-dye response are associated with those other 

 characteristics which permit us to designate fibroblast and macrophage cells. 



3. The mitochondrial apparatus of the connective-tissue cells can not be said 

 to be electively stained by means of the vital acid dyes. 



4. The vital-dye "granules" in the case of both fibroblast and macrophage 

 cells are neither chemical combinations of the d}-e with the protoplasm nor physical 

 tingeing of pre-existing cell-organs, but are actual accumulations within the cell 

 of the vital dyestuff in fluid, high-colloidal, flocculated, or crystalline form, in ac- 

 cordance with the conceptions of Evans and Schulemann. 



5. The ingestion of these dyestuffs is usually associated with their separation 

 from the living protoplasm by virtue of a segregating power of the cell; for such 

 segregation, granules, minute vesicles, and vacuoles of many sizes may be created 

 in addition to those already present in the cell. We have called the ensemble of 

 these structures the "segregation-apparatus" of the cell. 



'6. The power to store vital dyestuffs is, on the part of the macrophage, greatly 

 in excess of a similar capacity shown by the fibroblast cell. 



7. The macrophage vital-dye deposits are, conversely, more susceptible of 

 decolorization and less permanent than are the more minute deposits in the fibro- 

 blast cell. 



8. The brilliant vital stains which may be secured with the acid dyes bring to 

 view in an unmistakable way an underlying physiological difference in the macro- 

 phage and fibroblast cells, and in particular display their differing capacity to ingest, 

 segregate, and store substances of the same chemical or physical state as character- 

 ize solutions of the d3'estuffs belonging to the acid-azo class. 



