1492 Journal of Applied Microscopy 



In determining the photographic complement of a color it is more accurate 

 to make photographic analyses of stains and color screens than to make simple 

 visual analyses. 



The same plate and source of light must be used as in taking the photo- 

 micrograph, because, as shown above, plates of different makes may differ 

 greatly in their degree of sensitiveness to different parts of the spectrum, and it 

 is a well recognized fact that diflferent illuminating agents give different spectra. 

 The object for which one should strive in the analyses of stains and color screens 

 is to imitate as exactly as possible the conditions that will exist in the process of 

 photo-micrography. The spectrographs illustrated in Fig. 3 were made with 

 color screens in preference to cells of fluid, as the screens are much more con- 

 venient than cells, and are quite as satisfactory. The color screens are made 

 by soaking a cleared lantern slide in a solution of the desired stain until the 

 gelatin is saturated, then rinsing and removing the surface liquid with a cotton 

 pad. The screen is then dried and covered with a cover-glass as in mounting 

 a lantern slide. The depth of color in these screens is dependent upon the 

 degree of concentration of the staining solution rather than upon the length of 

 time the plate is soaked. c. w. j. 



Kresylechtviolett. 



In the Centralblatt fiir Bakteriologie, Vol. 27, Homberger describes a new 

 method of staining the Gonococcus by which it may be distinguished from all 

 other micro-organisms. The stain used for this purpose was Kresylechtviolett, a 

 fluorescing color prepared by Leonhard. In dilutions of 1-10,000 the water 

 solution of this stain colors the Gonococcus a reddish violet while other micro- 

 organisms are either not stained at all or take a faint blue tinge. Homberger 

 mentions further that mast-cells, amyloid, mucin and colloid are stained well with 

 this dye and that it can also be used in Gram's method. 



It was found on working with the stain in this laboratory that the water solu- 

 tions precipitate on standing and lose their staining power. The alcoholic 

 solutions did not precipitate, but satisfactory results could not be obtained with 

 them. Since the reactions obtained with the stain were found by repeated exper- 

 iment to be very characteristic, and as it promised to be a very valuable addition 

 to diagnostic methods the present work was undertaken at the request of Dr. 

 Warthin to find, if possible, a satisfactory method of using the stain, and to extend 

 its application in pathological work. 



The stain used was prepared by Griibler. It is soluble in water and alcohol. 

 After much experimental work the following method of preparation was found to 

 be satisfactory in all respects, and to meet all requirements, and is the one used 

 throughout this work : 

 Preparation (Morse) : 



Five per cent, aqueous solution of Phenol, - 80 c. c. 



Ninety-five per cent. Ethyl Alcohol, - - - 20 c. c. 



Stain, - - - 1 gm. 



