28 Effie A. Eead 



Histological Methods. 



Four methods have been used : the rapid Golgi, the mixed Golgi, gold 

 chloride, methylene blue and dissociation methods. 



The Rapid Golgi Method. — Fresh tissue was put into osmium-bi- 

 chromate mixture for 3-4 days and kept in the dark. 



3 per cent potassium bichromate 2 parts. 



1 per cent osmic acid 1 part. 



This was changed at least once. The material was then placed in % 

 per cent silver nitrate for 3 to 4 days, being changed several times in 

 the first half hour until no precipitate formed. Dehydration was as 

 rapid as possible, li/o per cent, 3 per cent and 8 per cent collodion was 

 used for infiltration. Tissue was left in 8 per cent collodion i/o day 

 without harm and was imbedded in 8 per cent collodion. It was 

 hardened in chloroform vapor for 2 to 12 hours. The knife and block 

 were fiooded with 95 per cent alcohol during the cutting; sections were 

 60 to 80 microns. 



The results were very good both in the dog and in the cat. Olfactory 

 cells, with their axones, peripheral processes and the olfactory hairs, 

 could be seen. Sensory cells were found in the vomeronasal organ of 

 the cat. In man the results were less satisfactory, due to the lack of 

 fresh material, but positive verification was obtained. 



The Mixed Golgi Method. — Good results were obtained in the dog and 

 the mouse from the mixed Golgi method. (The tissue was treated 

 as for the rapid method, except that it had been previously fixed in 

 Miiller's fluid.) The nasal conchge and the septum of this dog were still 

 cartilagenous, so it was possible to make sections through the entire 

 nose and olfactory Imlb. Nerves could be traced for a long distance even 

 through the cribriform plate to the olfactory bulb. Olfactory cells were 

 obtained and also sensory cells in the vomeronasal organ of the mouse. 



The Gold Chloride Method. — Both Eanvier's formic acid method and 

 Hardesty's modification of the gold chloride method were used. The 

 difficulty in the use of the former method is due to the fact that the 

 epithelium is very easily exfoliated in fresh material. Good results, 

 however, were obtained from human material by this method. Har- 

 desty's modification of the method- gave good results with dog and cat. 

 The dog material had been in 10 per cent formalin for eight years, the 

 cat only a few weeks. Sections were made from 1 to 20 microns. The 

 sustentacular cells were stained as well as the olfactory cells; in fact, the 



^Hardesty, Neurological Technique. 



