MS 34.1-MS 34.21 METAL STAINS 603 



removing any of the dichromate. It is safer silver nitrate solution. The brain is then 

 to leave the embiyo at least a week in this removed to a fresh hatch of at least 100 

 solution and desirable to change tlie di- milliliters of silver nitrate and stored in a 

 chromate at least once during this period, dark cupboard for from seven to ten days. 

 The brain may now be removed, placed on The bottle should be examined at daily 

 a pad of chemically pure filter paper, and intervals and the solution changed at any 

 left there until as much as possible of the time, whenever either a yellow precipitate 

 surface-adherent dichromate has l)een re- is accumulating at the bottom of the 

 moved from it. It is then placed in a clean bottle or a brownisli stain is appearing on 

 crystaUizing dish containing from 25 to 50 the sides. At the end of ten days the brains 

 milliliters of the silver nitrate solution, are removed to a large bottle of 95% al- 

 and rocked back and forth to prevent the cohol after having been cut in half by a 

 precipitate of silver chromate from set- sagittal section. They may remain in al- 

 tling on the surface of the brain. After cohol until required or, as soon as de- 

 about ten minutes of agitation, the now hydration is complete, may be sectioned 

 cloudy silver nitrate should be removed by the celloidin technique. These sections 

 and replaced with a fresh batch of silver are then cleared and mounted under cedar 

 nitrate; and the process repeated until no oil just as though they were Golgi 

 further precipitate washes off into the preparations. 



34.1 Staining Solutions 



In most cases, the two metals are supplied from separate simple solutions recorded under 

 the individual techniques. 



34.1 Amprino 1936 4285a, 13:223 



preparation: To 20 20% chromic acid add sHghtly more 10% potassium hydroxide 

 than is necessary to change color from red to yellow. Add 25 this solution to 75 10% 

 silver nitrate. Wash ppt., suspend in 100 water, and add just enough ammonia to 

 secure complete solution. 



34.1 Berkely 1897 10920, 6:1 



preparation: To 100 1% silver nitrate add 10 0.25% phosphomolybdic acid. 



34.1 Hill 1896 3464, 9:1 



formula: water 100, silver nitrate 0.8 gm., formic acid 0.1 



34.1 Juschtschenko test. 1933 Cajal and de Castro Cajal and de Castro 1933, 124 



formula: water 100, silver nitrate 2.5, osmic acid 0.5 



34.1 Kolossow 1897 test, da Fano 1928 Gatenby and Cowdry 1928, 608 



formula: water 100, silver nitrate 2, osmic acid 0.4 



34.1 Martinez 1931 te.<^t. 1932 Findlay 11360, 52:152 



preparation: To 50 10% silver nitrate add 50 2% sodium tungstate and then just 

 enough ammonia to redissolve the ppt. 



34.1 Oliveira 1936 22575,298:523 



prepar.\tion: To 5 10% silver nitrate add 10 5% potassium dichromate. Collect ppt. 

 and wash till washings are color-free. Suspend ppt. in 40 water and add just enough 

 ammonia to dissolve ppt. Dilute to 85. 



34.1 Renaut test. 1907 Bohm and Oppel cit. Regaud Bohm and Oppel 1907, 387 

 formula: water 100, osmic acid 0.15, picric acid 0.6, silver nitrate 0.25 



34.2 Neurological Methods 



34.21 nerve cells and processes 



34.21 Andriesen 1894 see MS 34.21 Golgi 1880 (note) 



34.21 Berkely 1897 10920, 6:1 



REAGENTS REQUIRED: A. F 7000.0000 Muller 1859; B. F 1700.0000 Berkely 1897; C. 

 0.25% silver nitrate; D. MS 34.1 Berkely 1897 



