THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 39 



The lessened solubility of the deposits produced by high colloidal dyes is open 

 to other explanations. Such lessened solubility may spring from the identical 

 cause of lessened solubility of the crystalline dilute-dosage deposits which can be 

 produced with some positive dyes, i. e., they may have developed an extraordinary 

 density merely because they are more slowly produced. This view would find 

 some support in the undoubted slower diffusion powers of the colloidal dyes as 

 well as in their lessened excretion. The diffusible part of the dye would con- 

 sequently be actually slowly applied to these cells in very dilute dosage over a 

 considerable period of time. This explanation, however, is negated by the rela- 

 tively large and quickly formed deposits which may be produced, for instance, in 

 the macrophages of the atretic follicles of the ovary when a high colloidal dye like 

 afridol blue is administered by the peritoneal route. The deposits are large in size 

 and quickly produced; indeed, an* extensive staining of the subcutaneous tissue 

 shows that fairly rapid diffusion has ensued. The deposits are also remarkably 

 permanent. It is hence certain that the higher colloidal dyes tend to make less 

 soluble accumulations within the cell. This would appear to be an inherent 

 physical property of the compounds in question comparable to their sensitivity 

 to electrolytes, absorptive power, etc., and it is a necessary field for future 

 investigation. 



In addition to these facts of the greater permanency of colloidal dye deposits 

 it is necessary to refer to the fact that a similar permanency also rarely characterizes 

 the deposits of certain very diffusible brilliant vital dyes of the azo series, sub- 

 stances which also establish a large vacuolar segregation-apparatus. In these 

 instances the dye deposits by no means remain in their pristine form and extent, 

 for much of the dye substance disappears on decolorization. A residuum of the 

 dye substance, however, would appear not to be able to escape the vacuolar-appa- 

 ratus where it undergoes a unique and interesting concentration to small concre- 

 ments. A great number of larger vacuoles are thus replaced by smaller, intense 

 amorphous masses. This peculiarity is exemplified by the behavior of vital new 

 red (figs. 84, 85). 



Protocol: Rat 312, injected intraperitoneally with a 1 per cent solution of vital new red, 

 1917, April 28, May 1, 7, 15, 24, 29, June 5, 9, 12, and 16, 0.5 c. c. each day; June 20 

 and 23, 4 c. c. each day. 



1918, March 20: Animal is stained a bright pink. Skin of thigh light pink. Under the low- 

 power, cell types can not be made out with certainty, but it is seen that a considerable number of 

 dense-red deposits occur in the great majority of the cells. 



Under the oil it is readily seen that the main mass of the dye is in the fibroblasts, where it 

 occurs in rather uniform-sized, deep-red, angular deposits. These vary in number from perhaps 15 

 or 20 to 75 or 80. Neutral red does not disclose any other bodies, or at most very few other bodies, 

 of the vacuolar type (fig. 84). It is evident that such deposits constitute a lifetime pigmentation 

 of these cells. 



The macrophages are distinguished by a sparser number of vital-dye deposits and by the 

 smaller size of these as a rule, though instances of large deposits in macrophages can be found. 

 Neutral red shows what is probably a normal vacuolar system in these cells. The reaction gives 

 at most a pale orange-color to these bodies and convinces us that they have lost their content of 

 the vital dye (fig. 85). 



While there thus occur specific differences in the deposits produced by various 

 dyes, it is also true that the manner of establishment of the dye granules in the 



