No. 3.] PERIPHERAL NERVES. 645 



a catgut bundle, one was observed fourteen, the other thirty-five days after 

 the operation ; no regeneration was noticed. 



No physiological examination was made in any of the above 

 experiments. 



(e) Nerve Flaps. — Letievant has recommended three opera- 

 tions which may be performed when there is loss of nerve 

 substance. Of these the m^aking of a flap from the central or 

 peripheral stump, or both, is the one more generally known, 

 and is one of the procedures usually mentioned in surgical 

 text-books. With a sharp knife or bistoury the nerve is split 

 for a distance equal to about the length of the nerve segment 

 lost ; the division beginning a short distance from the end of 

 the stump. One of the halves is cut free at its central end (if 

 the flap is made from the central portion), turned down, and 

 stitched to the peripheral stump. Letievant reports a case 

 where the method was employed (see case No. 17 of table). 

 The simplicity of the method has no doubt done much to win 

 for it approval. It must not, however, be forgotten that it is 

 open to a number of objections. In the first place, assuming 

 that regeneration of the peripheral end takes place through the 

 agency of axis cylinders, which bud from the nerves of the 

 central stump, and remembering that all experimental work 

 shows that it is necessary to create favorable mechanical con- 

 ditions for these down-growing axes ; I must call attention to 

 the fact that, after turning a flap on its base, the lower end of 

 the nerve fibres of the central segment are not in line with the 

 fibres in the flap, but are rather bent from the course of the 

 nerve at an angle of about 90°, an observation which can 

 easily be made after this portion of the operation has been 

 concluded. The down-growing axis cylinders are, therefore, 

 not guided toward the flap and thence to the peripheral end of 

 the nerve, but bud into the connective tissue surrounding the 

 peripheral end of the central stump, as is clearly shown in 

 longitudinal sections through this region. In the second 

 place, the flap degenerates completely (its connection with the 

 central end in no way retarding this) with a result that we 

 have a condition similar to the one where a nerve is implanted, 

 except that in the latter case a more favorable approximation 



