THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 29 



Fibroblasts are distinguished chiefly by the fact that T 148 has not interfered with the delicate 

 deep-blue crystals described before. These cells always contain, however, a considerable number of 

 large pink dye T 148 vacuoles. Instances of vacuoles surrounding crystals, as is usual in macro- 

 phages, are rare, though this phenomenon has begun to occur (fig. 64). 



EVIDENCE OF THE SIMILARITY IN NATURE OF THE FIBROBLAST AND MACROPHAGE 



"DYE BODIES." 



The peculiar behavior of the fiber-forming cells of the connective tissue toward 

 the vital acid dyes could hardly have escaped the notice of any acute observer work- 

 ing with these compounds. Goldmann, whose beautiful and extensive researches 

 must be regarded as preliminary exploratory efforts of classic importance, con- 

 cerned himself only with the predominant reactions secured by these dyes upon 

 cells under various normal and pathological conditions. With the establishment 

 of the conception of "pyroll cells" (our macrophages), and with his demonstration 

 of the participation of these cells in various reactive processes, his work will have 

 abiding worth, regardless of the lack of exact cytological scrutiny at many points. 

 In the preliminary publication of our larger work (Evans and Schulemann, 1914), 

 we indicated clearly that the fibroblasts enjoy a distinctive reaction to the vital 

 stain. This fact has since been investigated with varying degrees of precision 

 from two sources which have furnished several publications each — from the labo- 

 ratories of Aschoff and Maximow. From the pathological department of Freiburg, 

 and, especially, in the work of Kiyono (1914), has come an admirable critical 

 reworking of most of Goldmann 's field, but with improved discrimination as to 

 cell types. From the Petrograd laboratory, to which we are indebted for funda- 

 mental, clear-cut histological work, especially on the areolar-tissue cell types, we 

 have the papers of Tschaschin (1912, 1913) and his astonishing interpretation of the 

 mitochondrial nature of the dye deposits. If the facts concerning the macrophage 

 stain which we have carefully enumerated in this paper furnish, as we believe they 

 do, a convincing refutation of this viewpoint so far as it concerns the great pha- 

 gocytic cells, it will be of importance for us to ascertain what light the same type 

 of experiments can shed on the nature of the somewhat different reaction to the 

 vital stains displayed by the fibroblast cells. Tschaschin's opinion on the mito- 

 chondrial origin of the macrophage stain was admittedly weak in proof and would 

 appear not to have been taken seriously by most subsequent writers. It was 

 influenced confessedly by the conditions which he believed obtained in the fibro- 

 blasts. But in the last publication from Maximow 's hand (1916), Tschaschin's 

 teacher has been able to show a practically normal mitochondria] apparatus, even in 

 the phagocytic cells, merely by a more successful employment of iron-hematoxylin 

 stains on Zenker-formol material, and he himself has at least seriously weakened 

 his pupil's view that the mitochondrial apparatus in these cells is wholly devoted 

 to that granular and vacuolar transformation which Tschaschin looked upon as 

 occurring for the sake of storage of the vital dye. We have already instanced our 

 profound distrust of the specificity of fixed staining methods for the mitochondria 

 of these cells, and our success in the elective display of the mitochondria, even of 



