NORMAL MODE OF SECRETION IN THYROID GLAND 4/ 



protoplasm also stained bluish after formalin zcnker fixation, it 

 was difficult to define accurately the limits of the vacuoles, and 

 after fixation in ordinary Zenker's fluid the vacuoles did not 

 stain at all. Accordingly the indication was to find some stable 

 stain which would stain the protoplasm diffusely, and then to 

 stain the secretion a contrast color. For this puropse brasilin 

 in phosphotungstic acid solution was found to be effective. The 

 solution is prepared as follows: 



Phosphotungstic acid 1.0 ^. 



Distilled water 100.0 cc. 



Brasilin 0.05 g. 



The brasilin is first dissolved in a small quantity of distilled 

 water by the aid of heat and added to the phosphotungstic acid 

 solution. Ripening may be accelerated by the addition of 0.4 

 cc. of hydrogen peroxide, or of a few drops of a solution of soluble 

 molbydic acid. The solution deteriorates with age and should 

 not be used after three days. 



Sections of thyroid glands which have been fixed in formalin 

 Zenker, fastened to slides by the water method (if albumen is 

 used it should be very small in amount) are passed through 

 toluol, absolute alcohol, to water, iodised, and placed in the 

 staining solution from one to several hours. The sections are 

 then washed in water and placed for one to five minutes in the 

 following solution : 



Phosphomoh'bdic acid 1 -0 g. 



Wasserblau 0.2 g. 



Water 100.0 cc. 



Then wash rapidly in water, dehydrate in absolute alcohol, clear 

 in toluol, and mount in balsam. 



In the preparations so stained with brasilin and wasserblau 

 the cytoplasm stains pink to lilac, the nuclear chromatin, deep 

 red, and the contents of the vacuoles sky blue, as shown in Fig. 

 1. The colloid droplets of Hiirthle stain deep blue or deep red 

 according to the concentration of the gel which composes them, 

 which determines the diffusion rate of the dyes emplo^^ed. 



