7 1 6 HUBER. [Vol. XI. 



in the peripheral ulnar are surrounded by a medullary sheath, 

 and present the structural appearance of a normal nerve. 



VIII. After the 136th day in primary implantation between 

 the resected ends of a median, and the 149th day after the 

 same operation in the ulnar, the down-growing axis cylinders 

 have reached the peripheral part of the injured nerve, as shown 

 by physiological and histological examination. 



IX. The down-growing axis cylinders are found in the old 

 sheaths of Schwann in that portion of the fibres of the central 

 stump which underwent degeneration, within and between the 

 old sheaths in the implanted segment, and bear a similar rela- 

 tion to the old sheaths in the degenerated peripheral part of 

 the nerve. 



(b) Microscopical Appearances in Experiments of Tubular 



Suture. 



A study of longitudinal and cross-sections through the 

 region of the implanted bone tube in Exps. 27, 28, 29, with 

 periods of five, ten, and twenty days after uniting the ends of a 

 resected nerve with a bone drain, show that absorption of the 

 bone must take place very rapidly, as scarcely any portion of it 

 is found by the end of the tenth day, and no trace of it at the 

 end of the twentieth day. Even in the experiment of five days' 

 duration, the wall of the bone tube was so altered structurally, 

 that it bore very slight resemblance to decalcified bone. In 

 its place is seen a network of coarse trabeculae, very irregular 

 in shape and size, stained very deeply red, and presenting a homo- 

 geneous appearance in preparations hardened in Flemming's 

 solution, and stained in safranin and licht griin. The meshes 

 of this network are filled with polynuclear white blood cells and 

 connective tissue cells. (The bone drain used in the above 

 experiment was made from the ulnar of a chicken, the shaft of 

 which has only a thin layer of compact bone.) In the lumen 

 of the implanted bone tube, in the experiment of five days' 

 duration, is found a very loose connective tissue, rich in 

 spindle-shaped and branched connective tissue cells, and only 

 a few connective tissue fibrillae, irregularly interwoven, are 



