34 ON THE DIFFERENTIAL REACTION TO VITAL DYES EXHIBITED BY 



which would affect the fibroblasts in this way was a particular boon to our investi- 

 gation of the mitochondrial question as far as it concerned the fibroblastic cells, 

 for the morphology of the dye deposits in such cases does not resemble remotely the 

 mitochondria. Some of the most satisfactory of these dyes were red in color, thus 

 affording chromatic distinction between them and mitochondria tinged blue with 

 janus green. 



2. The data which we have given for macrophages on the phenomenon of 

 metachromasia and the proof it furnishes of the accumulation and flocculation of 

 the vital dye have all been found to hold in the case of the fibroblasts. Indeed, it 

 is a general rule that the accumulation, flocculation, or concrement formation, 

 just as is the case with crystals, is easier to produce in the fibroblasts, providing 

 our dosage is sufficient to get the dye into these cells. 



3. The question of whether or not the "dye bodies" represent preformed 

 cell-organs or are merely true accumulations of the dye, gains a convincing answer 

 in the case of the fibroblasts, just as it did for the macrophages, by the produc- 

 tion of pure dye-crystals in these cells. These are produced, as in the macro- 

 phages, by long-continued, greatly diluted dosage only with certain dyes (trypan 

 blue and its isomers). Evident increased permeability of the macrophages, when 

 compared with the fibroblasts, makes it necessary to employ only extremely dilute 

 solutions of the azo dyes if we would effect pure crystal pictures in the great pha- 

 gocytic cells. Such experiments, as we have already indicated, give us in fact an 

 elective crystal deposition in the macrophages. But if slightly higher dosages are 

 employed, both cell types in the skin are affected, the fibroblasts by pure crystalline 

 deposits, the macrophages by crystalline and colloidal deposits about equally 

 abundant; and by the continuation of such dosages the number of crystalline de- 

 posits in the fibroblasts can be greatly increased (fig. 73, 74, 75, 76). 



Protocol: Rat 46, injected intraperitoneally with a 1 per cent solution of trypan blue, 

 March 8, 11, 14, 18, 20, 23, 2G, 29, April 1, 4, 7, 10, 13, 16, 19, 22, 25, and 28, 1 c. c. 

 each day. 



May 1: Animal is stained a profound blue. Under the low-power, both types of cell are 

 heavily laden with deposits which seem, even at this power, wholly crystalline. Cell types are 

 magnificently differentiated. Macrophages are blue-black, except for the nuclear area. They 

 often lie in small colonies or chains of cells. Fibroblasts are a lighter shade of blue and the typical 

 cell outline with its delicate processes is accurately preserved by the dye deposits which fill them. 



Under the oil, macrophages usually have broad, blunt crystal masses of uniform size. Some 

 cells contain crystals of longer, more delicate form. Neutral red tinges the broad structures and in 

 some gives a picture of red, angular vacuoles with blue crystals distorting and protruding from them. 

 As a rule, the crystalline deposition has advanced so far that large, uniform-sized, triangular and 

 diamond-shaped, dense-blue masses, defeating an analysis, are the result. Some smaller rods lie 

 between the large, blunt structures (fig. 75). 



Fibroblasts have more delicate and longer crystals. At times these occur in groups and suggest 

 that they have distorted a vacuole. Neutral red stains the vacuolar portion first. It shows prac- 

 tically no new structures. Threads do not occur in the fibroblasts (fig. 74). 



Protocol: Rat 31-3, injected intraperitoneally with a 1 per cent solution of trypan blue, 

 February 8, 11, 14, 17, 20, 24, 26, March 1 and 4, 1 c. c. each day. 



March 5: Animal is stained a deep blue. Subcutaneous tissues are deep blue. There is a 

 small area stained blue-black at the injection-point. Under the low-power a magnificent staining 

 of all cells is seen. Deposits are deep blue and too small to be seen individually with the low-power 

 except for scattered large, blue vacuoles evidently in macrophages. Cell types are distinguished only 



