30 ON THE DIFFERENTIAL REACTION TO VITAL DYES EXHIBITED BY 



badly overloaded "polyblastic" cells, by means of the method of supravital stain- 

 ing after sufficiently patient empirical efforts with various concentrations of janus 

 green B. 1 



It is in the fibroblasts, however, that Tschaschin has announced his discovery 

 of an elegant and purely elective tingeing of the mitochondrial apparatus of the 

 living cell by means of the vital azo dyes, and even those observers who feel corn- 

 polled to view with skepticism his stand on the macrophage question have been 

 inclined to accept or have refrained from criticism of his theory of the mitochon- 

 drial identity of the "dye bodies" in the fibroblastic cells (cf. especially Kiyono). 

 Aside from the fact that no such affinity between mitochondria and the azo dyes 

 can be demonstrated in any other cells or tissues, Tschaschin 'a interpretation is 

 fortunately open to direct examination by specific supravital staining of the mito- 

 chondria, such as we have carried out in the macrophage cell. We can not resist 

 again the opportunity to remark on the inadequacy of other agents for the elective 

 display of the mitochondria. Neither the hematoxylin, the alizarine, nor the 

 fuchsin methods will accomplish this end, for with all three of them the segregation- 

 apparatus, whether in granular or vacuolar form, is, to varying degrees, tinged. 

 These facts, in our estimation, have led Maximow in his latest tissue-culture studies 

 (1916), to trace erroneously a connection between these two cj^toplasmic structures. 

 Our own position is wholly that taken by the Lewises, who, after extensive cyto- 

 logical analyses of the same material (cultures), are positive in their statements of 

 the possibility of precise separation of the vacuolar and mitochondrial elements 

 by supravital tinctorial methods (neutral red, Nile blue B, brilliant cresyl blue, 

 janus green). Indeed, no other methods than the last will bring conviction here, 

 for neither criteria of size, distribution, or morphology are anything but confusing 

 in precisely this field. We must confess that the behavior of the areolar fibro- 

 blasts of the rat towards trj r pan blue and some of its isomers gives us dye bodies 

 which with striking versimilitude reproduce the mitochondrial pictures obtained 

 by most methods; but one of us (Scott, 1915) has already reported the successful 

 demonstration of the true mitochondrial system in such fibroblasts stained to vary- 

 ing degrees with isamine or trypan blue, and where the azo-dye bodies resemble 

 closely mitochondria and the figures supplied by Tschaschin. Even in the case of 

 normal tissue, the descriptions of Dubreuil (1911-1913), Maximow (1916), and 

 others of the mitochondrial apparatus of fibroblasts are, none of them, quite ac- 

 curate on account of the lack of specificity of their methods and consequently 

 of the inclusion of other cytoplasmic structures, even though these are not very 

 abundant in fibroblastic cells. For this reason it is perhaps not unessential that 

 we present carefully executed drawings of the normal appearance of fibroblast 

 mitochondria, carried out by the supravital method on living cells (figs. 65 and 66). 



The circumstances which hinder a supravital demonstration of mitochon- 

 dria in the macrophages of animals deeply stained with azo dyes operate to de- 

 feat our success with fibroblasts, for the tissue-juices, charged with the acid dye, 



1 With which we would place, in addition to the other janus dyes investigated by Cowdry, methylene violet B A (Hocchst) 

 and amethyst violet (B. A. S. F.) 



