GOLGI BODIES, ETC. 321 



spinal ganglia of mice and rats, the pituitary body of the same 

 animals, etc. Pieces of spinal cord, cerebrum, cerebellum of adult 

 animals give better results if fixed for about eight to ten hours. 

 The fixation may be prolonged in special cases to twelve to twenty 

 hours, but should not exceed twenty-four hours. The fixation 

 in an incubator at a temperature varying between 25° and 37° C. 

 has been attempted with success in the case of tissues of adult 

 subjects, but it leads to a staining of both the internal apparatus 

 and intracellular formations, which, according to their morphology 

 are to be considered as mitochondria. 



For the impregnation. Da Fano quickly washes the pieces in 

 distilled water, makes their surfaces smooth if necessary, and then 

 places them into 1-5 per cent, silver nitrate in the dark for twenty- 

 four to forty-eight hours at room temperature. For very small 

 fragments, 1 per cent, silver nitrate may be used, whilst for pieces 

 of spinal cord of adult subjects, 2 per cent, should be preferred. 

 For the reduction he uses Cajal's hydroquinone-formalin mixture, 

 taking care in further recutting the pieces before transferring 

 them into the reducing fluid, so that their thickness should not 

 exceed 2 mm. He dehydrates, clears in cedar oil and imbeds 

 pieces, preferably in paraffin, or he makes sections by the freezing 

 method. He usually tones these by means of 0-2 per cent, gold 

 chloride, fixes with 5 per cent, sodium hyposulphite, counter- 

 stains and mounts as usual. 



The method gives good results also with material from lower 

 vertebrates and invertebrates. 



725. Cadmium Chloride Formol Golgi Apparatus Method (F. 

 AoYAMA, Zeit.f. wiss. Mikr., 1930). Fix small pieces of tissue in 

 cadmium chloride 1 c.c, formol, neutral 15 c.c, distilled water 

 85 c.c, for three or four hours. Rinse quickly in two changes of 

 distilled water, and transfer to 1-5 per cent solution of silver 

 nitrate for ten to fifteen hours at 22° C. Rinse quickly in two 

 changes of distilled water, preferably in a dark room, and transfer 

 for five to ten hours to the reducing solution (hydroquinone 1 part, 

 neutral formol 15 c.c, distilled water 85 c.c, 0-1 to 0-15 gm. 

 of sodium sulphite, sufficient to produce a yellowish tinge). Wash 

 thoroughly in tap water, upgrade, imbed and section. The 

 sections may be counterstained in carmine or hsematoxylin and 

 eosin. Cold-blooded animals need longer fixation and impregna- 

 tion than warm-blooded, for which the above given times are 

 suitable. 



After having seen preparations of various vertebrate and in- 

 vertebrate tissues made by this method, we have concluded that 

 it is the best of the three silver formalin methods, and the nearest 

 approach to a good osmic Golgi technique. It is reliable, remark- 

 ably specific, and causes less incrustation of dictyosomes than other 

 silver methods. 



VADE-MECUM. 11 



