No. 3-] AUDITORY OR HAIR-CELLS OF THE EAR. 447 



solution. In this the ears remained for 24 hours without change 

 unless the liquid grew turbid. As a rule one change is required. 

 Having tried various times, from 16-56 hours, I find that if 

 the ear stains at all, it will do so after a bichromate bath of 

 24 hours, and as a rule anything less gives an incomplete stain. 

 More variation in the stain is produced by varying the time 

 of the silver bath, but a good and uniformly satisfactory period 

 was found to be 24 hours. Successive transfers, from the 

 silver bath back to bichromate, were not productive of any 

 completer stain than had resulted from the 24 hours of 

 immersion in the bichromate and silver baths respectively. 

 Two strengths of silver bath were used, 0.50 per cent and 

 0.75 per cent. If there was any difference it was in favor 

 of the stronger solution. The silver bath was changed as 

 often as it became turbid from suspended crystals, and ears 

 were washed in used silver bath before being put in the full 

 strength solution. 



The penetration of the solutions is aided materially by 

 increase in temperature, and a warm oven may be used with 

 advantage, though it is not necessary. 



It may be well to repeat that where calcareous matter was 

 present in the ears they uniformly failed to stain, and I con- 

 sider the bone tissue of the adult ear the main source of 

 trouble in attempts to stain the adult cochlea by the Golgi 

 method. It acts as a sure preventive as the method is now 

 applied. The following paper is descriptive of Golgi prepa- 

 rations, and the conclusions possess only the weight which 

 belongs to this important method. But it must be borne in 

 mind that while this silver stain reveals details of structure 

 in complicated arrangements with a distinctness unsurpassed, 

 it at the same time conceals some of the relations of the very 

 things so clearly set forth. 



A. The Hair cells of Corti's Organ or the Mammalian Cochlear 



Organ. 



The organ of Corti is a very complicated structure, but it 

 has received during its differentiation no new elements, for 

 the arch of Corti is not to be looked upon as a new struct- 



