Journal of Applied Microscopy. 435 



Physiolog}- is in a transitional stage from text-book work, illustrated by appar- 

 atus and organs of animals dissected in class for the first half of the course, giv- 

 ing the student a fair idea of the skeletal and muscular systems, a more thorough 

 knowledge of the alimentar}-, circulatory, respirator}-, and excretorj' systems : 

 then hygiene and sanitation, closing with what to do in case of emergencies. 

 This is followed by a course devoted entirely to laboratory work on the gross 

 structure and composition of bones, levers of the body illustrated, microscopic 

 examination of muscles, tests for known food-sfufls, applied to find which of these 

 are present in common foods, the changes taking place in germinating starchy 

 seeds, a few digestion experiments, and one culture of common bacteria and 

 yeast. L- MuRBACH. 



Detroit, Mich., June, 1899. 



Preparing Sections of Cochlea for Microscopical 

 Examination. 



In preparing sections of the inner ear many difficulties arise which must be 

 overcome before the work is at all satisf actor)'. The greatest difficulties we 

 have found are those of orienting the material in the desired way, and keeping 

 the material in its normal condition. 



Having met with good success in obtaining sections of the inner ear, we 

 here give our method of work. 



We have found the best materials for the work to be the ears of young pups, 

 and kittens, about two weeks old. We take the temporal bones from the animals 

 as soon as the animals are dead, separate the petris bone from the rest, and place 

 them in five per cent, nitric acid until they are thoroughly decalcified. The acid 

 acts both as a killing and a fixing agent, and removes the mineral matter from the 

 bone. 



We have used the celloidin and paraffin methods extensively. We find the 

 paraffin method by far the best, as it preserves the material in its normal condi- 

 tion. The celloidin method is good for general characters, but the shrinkage 

 ■which must necessarily result when the celloidin has hardened, causes the mem- 

 brane of Reissner, and the basilar membrane to be folded. 



We have used many stains, and have obtained the best results with borax 

 carmine in toto, and picric acid on the slide. The acid is especially good to 

 bring out the hairs of the hair cells. We here give in detail the steps taken in 

 the work. When the material is thoroughly decalcified place it in : 



(a) Rinse water for eight hours. 



(d) 35 per cent, alcohol, three hours. 



(c) 50 per cent, alcohol, six hours. 



(d) Now take the material from the alcohol, and with a sharp razor make 

 free-hand sections of the material in the direction desired. If the desired view- 

 is a longitudinal one, cut thin slices parallel to the auditor)- nerve and the 

 modialis. This is easily done, as the spiral of the cochlea can be plainly seen 



