124 



Messrs. H. 0. Feiss and W. Cramer. [Oct. 22, 



kept in Einger's solution there was more detritus, and the myelin in many 

 of the fibres showed a lack of clearness in its staining reaction. This 

 appearance of the myelin might be described as " flaky," while that of the 

 fibres degenerated in vivo might be referred to as " laked." 



Paraffin sections, made from the specimens kept in Einger's solution, were 

 stained with liEematoxylin, and showed the nuclei broken up and staining badly. 



The next group of experiments was carried out in order to determine the 

 effect of temperature on the changes which nerve fibres undergo in vitro. 



Group III. — Comparison of Excised Nerves hept in Ringer's Solution at 37° and 



at 5° respectively. 



External popliteal nerves were removed aseptically. Each nerve was 

 divided into two pieces and placed in Einger's solution in Petri dishes. One 

 set of dishes was placed in the incubator, the other set placed in the ice box. 



At the end of four and six days the nerves were removed and placed in 

 1-per-cent. osmic acid. 



Microscopical Findings. — The nerves kept at 5° showed the characteristic 

 changes in the myelin sheath, but these changes were not as pronounced as 

 those seen in nerves kept at 37° for the same lengths of time. 



The next group of experiments was devised in order to test whether 

 contact with an aqueous solution was a contributory factor in bringing about 

 these changes in the myelin sheaths. Attempts to keep nerves in the 

 incubator in a moist chamber for several days, so that they were hanging 

 freely in the chamber and did not come into direct contact with the 

 solution, did not give very satisfactory results, because the nerves dried 

 partially. The object of this group of experiments was attained, however, by 

 immersing the nerves in liquid paraffin. 



Group IV. — Comparison of Excised Nerves hept at 37° in Ringer's Solution with 

 Excised, Nerves kept in Liquid Paraffin. 



External popliteal nerve removed from an adult cat under sterile pre- 

 cautions, and divided into two pieces. One piece was placed in Einger's 

 solution. The second was placed in liquid paraffin. Both specimens kept at 

 37°. Pieces removed at end of six days and fixed in 1-per-cent. osmic acid. 



Microscopical Findings. — The specimen kept in Einger's solution showed the 

 characteristic signs described above under Group I. The specimen kept in 

 liquid paraffin consisted for the most part of apparently normal fibres. 



