157 



IV. — Method for the Demonstration of the Golgi Apparatus 

 ill Nervous and other Tissues. 



By C. Da Fano, M.D., L.D. on Morbid Anatomy, University of 

 Pavia (Italy), F.E.M.S., Lecturer on Histology, King's College, 

 University of London. 



(Bead March 17, 1920.) 



One Plate. 



The preparations I have the honour of showing to this Society 

 have all been obtained by the following method : — 



1. Fixation. 

 Small pieces of quite fresh tissues are fixed in — 



Cobalt nitrate ...... 1 grm. 



Distilled water 100 c.c. 



Formalin ....... 15 c.c. 



The solution can be prepared beforehand and keeps unaltered 

 for months. Formalin need not be neutralized unless strongly 

 acid or containing free sulphuric acid, in which case it is neces- 

 sary to neutralize it by one of the usual i methods, such as shaking 

 with calcium carbonate and filtering before using. For the fixation 

 of embryonic organs, and in all cases in which a shrinkage of 

 delicate tissues is to be feared, the quantity of the formalin may 

 be reduced to 10, 8, 6 c.c. for every 100 c.c. of distilled water. 

 The pieces, about 3 mm. thick, are generally left six to eight hours 

 in the fixing solution at room temperature. This time should 

 be shortened to 3-4 hours, or even less in the case of certain 

 tissues, such as cartilage, or of very small pieces, such as spinal 

 ganglia of mice and rats, adrenals of mice, the pituitary body of 

 the same animals, etc. Hollow organs, such as the stomach and 

 intestine, are better fixed if partially filled with the fixing fluid 

 and kept in it in toto for about one hour, after which time they 

 are reduced to due proportions and treated according to their 

 thickness. 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 12-20 hours, but 

 should not exceed twenty-four hours. For the difficult fixation of 

 the testis of mammalia it is advisable to inject the fluid through 

 the abdominal aorta and afterwards to plunge the entire organ in ' 

 the fluid for some time before proceeding to cut off the necessary 

 pieces. Small animals can be injected in toto from the heart, 



