Maech 30, 1917] 



SCIENCE 



319 



that the muscle has been paralyzed by the di- 

 vision of all of its nerve supply. In all of the 

 experiments, unless otherwise stated, the cen- 

 tral connection of the nerves remained intact. 



1. In the first series of experiments all of 

 the branches of a nerve to a muscle were cut 

 and then reimplanted into the same muscle. 

 In the second series, after the wide excision of 

 all of the nerves to a muscle, a motor nerve 

 which supplied another muscle was cut and 

 implanted into the paralyzed muscle. 



It was found in all these experiments that 

 after from eight to ten weeks, electric stimu- 

 lation of the implanted or the reimplanted 

 nerve was followed by a good contraction of 

 the muscle. 



Conclusion. — In agreement with Heineke, 

 Erlacher and Steindler, direct neurotization of 

 a muscle paralyzed by separation from its 

 motor nerve supply is possible. After eight to 

 ten weeks, the connections between the nerve 

 and the muscle fibers have been reestablished. 



2. Eight weeks after the resection of all of 

 the nerves to a muscle, the wound was re- 

 opened and the muscle was examined. The 

 muscle appeared pale and shrunken, and woiold 

 not contract or would contract only very weakly 

 upon direct stimulation by a strong electric 

 current. A motor nerve from another muscle 

 was then divided and was implanted into the 

 atrophied muscle. 



Eight to ten weeks later the muscle had re- 

 gained its normal appearance, and electric 

 stimulation of the implanted nerve was fol- 

 lowed by a good contraction of the previously 

 atrophied muscle. 



Conclusion. — Neurotization of a muscle 

 which has been deprived of its nerve supply 

 for many weeks is possible. The muscle tissue 

 regularly regenerates imder the influence of 

 the regenerating motor nerve which has been 

 implanted. 



3. (a) Into a muscle with its nerve supply 

 intact, the motor nerve from another muscle 

 was implanted. 



Eight to ten weeks later, stimulation of the 

 normal motor nerve to the muscle caused a 

 good contraction, while stimulation of the im- 

 planted nerve was without result. 



(&) The normal nerve to the muscle was then 

 widely resected and the wound closed. When 

 the wound was reopened eight to ten weeks 

 later, the muscle had a normal appearance, and 

 the normal nerves to the muscle had not re- 

 generated. Now, however, a powerful con- 

 traction of the muscle followed the electric 

 stimulation of the implanted nerve. 



(c) In a few of the experiments described 

 under (a) stimulation of the implanted for- 

 eign nerve caused a contraction of the muscle, 

 but the muscle could no longer be made to con- 

 tract when its normal nerve was stimulated. 



Conclusions. — Hyperneurotization of a nor- 

 mal muscle is impossible. A normal muscle 

 can not he made to talce on additional nerve 

 supply. The implanted nerve can not make 

 any neuro-motor connections and its stimula- 

 tion will usually fail to have any effect upon 

 the muscle. If, however, the muscle is perma- 

 nently separated from its original nerves, then 

 the implanted nerve — which had been hitherto 

 unahle to form a connection with the muscle 

 fibers — will establish neuro-muscular connec- 

 tions, and electric stimulation of the nerve 

 will soon cause normal contractions of the 

 muscle. 



4. (o) The same experiment as in No. 3 (a) 

 was performed, namely, the motor nerve from 

 another muscle was implanted, and in addi- 

 tion the normal nerve to the muscle was cut 

 outside of the muscle and the ends of the cut 

 nerve at once united again by suture. 



After eight to ten weeks, stimulation of the 

 implanted nerve was without result, while stim- 

 ulation of the normal nerve to the muscle 

 (which had been divided and at once united 

 by suture) either above or below the point of 

 division caused a good contraction of the 

 muscle. 



(b) Both the foreign implanted nerve and 

 the normal nerve to the muscle were cut and 

 the ends of each at once united by suture. 



After eight to ten weeks, electric stimiilation 

 of the normal nerve either above or below the 

 point of division and suture, caused a contrac- 

 tion of the muscle. Stimulation of the im- 

 planted nerve was without effect upon the 

 muscle. 



