THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 23 



apparently can not increase as rapidly as would be the case were they formed de novo in the fibro- 

 blastic cytoplasm. Prolonged dosage of this case will, however, probably force them to break their 

 vacuolar boundaries and grow, but even with this occurring they will still fail to occupy all of the 

 vacuoles present, the tendency of trypan blue being here clearly proven to condense in fewer centers. 



Same animal, given further treatment with a 1 per cent solution of trypan blue, May 29, 

 31, June 2, 4, 6, 8, 10, 12, 14, 16, 19, 21, 23, 25, 27, and 29, I c. c. each day. 



July 9: Animal is stained a deep blue. Films taken from the middorsum, oyer the spinal 

 musculature. They are deep blue macroscopically. Under the low-power brilliant blue dye 

 deposits are seen in all macrophages. The elongated character of these seems evident even at this 

 power. The fibroblasts are also invariably evident at the low power, carrying a paler and sparser 

 blue content. 



The oil shows that cell types are easily distinguished by the usual difference of cell morphology, 

 as well as by the nature of the dye deposits. The macrophages have the majority, if not all, of 

 their vacuoles, which are of an intermediate, fairly uniform size, converted into angular structures 

 frequently elongated in only one dimension (spindle-shaped), but often multipolar. The very deep 

 blue color is uniformly distributed in these vacuoles, although an accentuation along one edge (the 

 crystals) can often be made out. 



The fibroblasts, although occasionally having a few deposits as large as the average of those 

 in the macrophages, have typically smaller, usually elongated ones. The larger accumulations have 

 the angular character and the deeper boundaries or cross-structures existing within them that 

 characterize the macrophage vacuoles and are to be interpreted as distorted vacuoles clue to the over- 

 growth of crystals which have formed within them. Occasionally deep, small, linear deposits of 

 trypan blue are connected by threadlike structures, and this would seem to indicate that the 

 crystals may form on these structures. Neutral reel shows that there are a good many T 148 

 vacuoles that still escape much contamination with the blue. 



Protocol: Rat 53, injected intraperitoneal^ with 0.1 per cent solution of dye T 148, March 

 1 to 4, inclusive, 6, 7, 8, 10 to April 14, inclusive, 1 c. c. each day. 



April 15: Subcutaneous tissue from thigh examined. Animal is stained a deep pink. Skin of 

 thigh is bright pink. Under the low-power, both types of cell are seen to be filled with pale-pink 

 vacuoles. 



Under the oil, the fibroblasts have their cell-body processes outlined by the possession of im- 

 mense numbers of small, faint-pink vacuoles, among whicn now and then the short, deep-red, 

 crystalline rods characteristic of this dye are found. These are abundant in some cells. It is 

 surprising that they may be entirely lacking in others. While the majority of the crystals are 

 probably between the vacuoles, some are clearly connected with the vacuoles with which they have 



formed. 



The macrophages are distinguished by the possession of uniform-sized, round, somewhat 

 larger vacuoles with the usual occurrence of much larger ones. These cells contain very much more 

 dye than the fibroblasts, judging by their general color, which is an emphatic pink, while the fibro- 

 blasts are merely tinged. The macrophages frequently contain in their vacuoles concrements of 

 the dye. Neutral red 1 : 5,000 gives a striking macrophage reaction, staining the vacuoles of these 

 cells a light brick-red, whereas the vacuoles of the fibroblasts are still pale in color. No crystals are 

 found in the macrophages, unless we except an occasional small rod present in a vacuole. 



It is evident that crystals have been produced by the saturation of the cell with dye. 



The same animal was injected intraperitoneally with a 0.5 per cent solution of trypan 

 blue, April 16 to 19, inclusive, and 21, 1 c. c. each day. 



April 22: Autopsied. Animal is stained a deep blue. Subcutaneous tissues are deep blue with 

 purplish tinge. Under the low-power there is a multiplicity of deposits in all cells and an evident 

 bluing of most of the macrophages. 



Under the oil, the fibroblasts have not stored appreciable amounts of blue dye. Short blue rods, 

 almost invariably in vacuoles, are occasionally encountered. Infrequently there are a few larger 

 vacuoles which contain blue crystals, and a scattered muddying by trypan blue of the T 148 vacuoles 

 can be found on searching. 



Macrophages are characterized by the contamination of a part of their vacuolar system by the 

 blue dye, which, in addition to the diffuse coloration of vacuoles is found condensing, sickle-like, 

 as deep-blue trypan crystals at the vacuoles' edges (fig. 47). Abdominal macrophages do not 

 display these sickles, which are so frequent a phenomenon in the thigh and thorax, but contain 

 chiefly pink, lilac, and purple vacuoles, in some of the largest of which are blue crystals, as well as 

 red and blue concrements. Red concretions and crystals occur now and then in vacuoles in all 

 parts studied (fig. 48). 



