THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 17 



2. The facts which one of us in conjunction with Schulemann was able to 

 establish concerning the metachromasia exhibited by some of these dyes (Evans 

 and Schulemann, 1915) have been examined by Schulemann (1915) with reference 

 to the probability with which we can affirm chemical or physical causes to underlie 

 this color change. It will suffice to remark here that what we have instanced as 



NH, 

 Nq0 5 5 N =U-( X )- N=N " 



occurring with Congo rubine, ^K^X^ L JkJ occurs with no 



NH 2 



"00 



NqOjS 



less than 12 dyestuffs of the benzidine group, 1 in all of which there takes place to 



a variable degree a color change in the dyestuff stored in the segregation-apparatus 



in accordance with coaguluative changes in the high colloidal solutions there present. 



Protocol: Rat 89, injected intraperitoneally with a 0.5 per cent solution of the lilac-colored 

 dye 150 synthesized for the comparative studies of Evans and Schulemann by com- 

 bining 1 molecule of benzidine monosulphonic acid with 2 molecules of 2-amido-8- 

 naphthol-6-monosulphonic acid, and hence with the formula 



OH OH 



tfr"^ N= £Cr 



April 11 to 26, inclusive, 1 c. c. each day. 



April 28: Animal is stained a fairly deep lilac. Subcutaneous tissue is pale lilac. Urine is 

 pale lilac. Low-power shows small bluish deposits in macrophages. 



Under the oil, fibroblasts are not at first apprehended, but on careful searching it is possible to 

 make sure that these cells carry a scanty content of small, pale-lilac vacuoles with some denser 

 deep blue. Neutral red shows an increased number of small vacuoles, but never gives any large 

 number, even in the most crowded cells (40 to 80). Janus green shows normal mitochondria. 



The macrophages are distinghished by the possession of small blue-lilac deposits, which are in 

 the form often of deep-blue concrements in vacuoles. Some of the larger vacuoles show a distinct 

 reddish tint. Neutral red discloses a fair number of small vacuoles not seen before. Janus green 

 shows normal mitochondria. 



These coagulative changes, concretions, or concrements, as we have variously 

 designated them, are again to be separated from true crystallization processes 

 which may or may not be associated with change of color, and to which we will now 

 refer. 



3. In the employment of dyestuffs which have such a colloidal state that even 

 minute quantities of them, after their segregation from the protoplasm, remain 

 anchored in the cell with great permanency, we have the means at hand to produce, 

 by very dilute dosage, minute dye deposits which are almost entirely true concre- 

 ments, while no significant enlargement of the segregation-apparatus occurs. (See 

 figs. 28, 35, 36, 37.) 



1 The behavior of these substances is identical in principle with that shown by Congo rubine. They were to be described 

 in full in our larger publication ("The Phenomenon of Vital Staining with Acid Azo Dyes," Evans, Schulemann, and 

 Wilborn) and arc given by Schulemann (1917). It is remarkable that von Mollendorf (1914) has sought to interpret our 

 proof that the dyes gradually solidify in their places of deposit as a supposition on our part that the dye deposits are always 

 granules of the solid dye substance! We had described in explicit terms our conception of the formation of vacuoles in the 

 genesis of vital granules in the protoplasm of vitally stained cells (EvanB and Schulemann, 1915). 



