122 Messrs. H. O. Feiss and W. Cramer. [Oct. 22, 



life of the animal and the life of the nerve fibre — were either both operative 

 or both excluded. It is quite conceivable, however, that the conditions which 

 are preliminary to the occurrence of Wallerian degeneration can be established 

 in a living animal but not in a dead animal, and that, when these conditions 

 are established, the degenerative changes in the nerve fibre itself might 

 proceed irrespective of the life of the fibre. 



Such a possibility is mentioned here in order to indicate that the life of 

 the animal and the life of the nerve fibre are two factors, whose influence on 

 the process of Wallerian degeneration may have to be considered separately. 



In order to obtain conclusive evidence to what extent the processes of 

 Wallerian degeneration are dependent upon the life of the nerve-fibre, it 

 seemed desirable to carry out observations on the behaviour of nerves 

 removed from the body and subjected to various conditions. 



Part II. — Experimental. 



The nerves studied in these experiments were the sciatic or popliteal 

 nerves of adult cats. For stains osmic acid was used for the myelin 

 sheaths and heematoxylin for the nuclei. The osmic acid preparations were 

 made by placing the nerves in a 1-per-cent. solution of osmic acid for 

 24 hours and then washing them for 24 hours. A small piece of the nerve 

 was then removed for teasing, and the remainder was usually embedded in 

 paraffin. 



For studying the Marchi reaction, the specimens were placed in Midler's 

 solution for one week, and then in a mixture of two parts of Midler's and 

 one part of osmic acid (1 per cent.) for three or four days, these steps being 

 carried out at 40° C. 



All the experiments on living cats were done under complete chloroform 

 anaesthesia, and with careful aseptic precautions if the animals were to be 

 kept alive after the operation. 



The composition of the Einger's solution used was as follows : — Sodium 

 chloride, - 9 grm. ; potassium chloride, 0"1 grm. ; calcium phosphate solution 

 (saturated), ad 100 c.c. 



Group I. — Excised Nerves Kept in Ringer s Solution at 37° for Various 



Periods. 



The right sciatic nerve of an adult cat was removed under chloroform, 

 using very careful aseptic precautions. The nerve was divided into five 

 pieces, each about | inch long. Each piece was placed in a sterile Petri 

 dish containing sterile Einger's solution, and all the dishes placed in an 



