18 ON THE DIFFERENTIAL REACTION TO VITAL DYES EXHIBITED BY 



Protocol: Rat 10, injected intraperitoneally with a 0.5 per cent solution of vital new red, a 

 brilliant orange-red tctrasulphonated azo dye with the following formula: 



:<^> 



NH C HN 



N Q 3 S- r ^Y> N <ru 5°j N 



uu 



CH. 



April 10 to 19, inclusive, 1 c. c. each day. 



April .' ': Animal is stained a brilliant crimson. Skin of thigh is a pale crimson. With the low- 

 power, one is easily able to distinguish cell types, the trails of minute red granules representing 

 fibroblasts being in conspicuous contrast to the agminations of larger, brilliant red granules which 

 mark the macrophages. 



Under the oil this distinction of cell types is confirmed. There arc a relatively small number of 

 deep-red angular bodies in the fibroblasts. The majority of these are small, but a few attain greater 

 size and tend to resemble crystalline plates, though none is very large (fig. 37). Neutral red stains 

 but few additional bodies, if any. Janus green stains normal mitochondria, affording a brilliant 

 contrast to the red deposits. 



The macrophages contain no very large deposits. The larger vacuoles, which show con- 

 spicuous peripheral agminations, arc of fairly uniform size (fig. 35). Some are a diffuse bright red, 

 but most of them show 3 to 7 or 8 bright-red, clearly outlined concrements of some refractivity. 

 There arc many concrements of this sort distributed free throughout the cytoplasm, having evidently 

 arisen from minute vacuoles. Very few pale deposits can be found, most present being brilliant red. 

 Neutral red shows a number of palely stained vacuoles which contain some of the apparently free 

 concrements (fig. 3G). 



Protocol: Rat 101, injected intraperitoneally with a 0.1 per cent solution of vital new red. 

 April 24, 27, 30, May 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, June 2 and 5, 1 c. c. each day. 



Jxtly S: Animal is stained a light pink. Subcutaneous tissue of thigh pink. Under the low- 

 power, one finds minute, deep-red deposits apparently in all cells, but types can not be distinguished. 



The oil confirms the impression that both cell types are involved ; the granules are intense deep 

 red, but there are always somewhat more in the macrophages than in the fibroblasts. Even in the 

 macrophages these deposits have a somewhat angular morphology and are to be interpreted as con- 

 cretions of dye. Neutral red 1 : 10,000 gives its customary reaction with the macrophages, making 

 cell types much more easily distinguishable. 



The fibroblasts contain from 8 to 25 of the deep-red dye concretions (the macrophages at least 

 five times this number) ; but neither size nor morphology of the deposits varies with the cell types. 

 Neutral red enables one, in the case of the fibroblasts, to ascertain that besides the dozen or more 

 evident deep-red deposits there is an additional equal number of small vacuoles which now stain a 

 weak orange. Janus green gives a brilliantly elective stain of mitochondria. 



When, in addition to these adhesive traits, the d} r e substance is also one that 

 easily crystallizes, the method of prolonged, very dilute dosage yields another set 

 of unique effects, namely, the appearance of minute, true crystals of the dye within 

 the cell. These have affected the pre-existing vacuolar apparatus of the macro- 

 phages but slightly, but the crystals are easily seen rimming part of the contour of a 

 tiny vacuole as an intensely colored crescent. Many of them, however, condense at 

 points evidently not previously the site of a vacuole, and consequently are built 

 up free in the protoplasm, from which they are never separated by vacuolar walls. 

 Such are the appearances when one administers over a period of weeks or months 

 small intraperitoneal doses of a 0.1 per cent solution of trypan blue to full-grown 

 rats. The palest hue of general color eventually characterizes such an animal, 

 but this is not, of course, due to the slightest trace of dyestuff in the body-fluids or 

 tissue-juices, but solely to the beginning accumulation of these minute, dense-blue 

 crystals, at first exclusively in the macrophage cells. (See fig. 38.) 



