THE NEURO-MUSCULAR SPINDLE 141 



SUMMARY 



The nerve endings arise early in embryonic life. The axones 

 grow out from the cells of the sensory gangha into the premuscle 

 mass. Here they form an intricate plexus, so as to bring the 

 muscle cells in contact with the end of the nerve. The axone 

 becomes attached to the myoblast by the simplest kind of a 

 neurofibrillar net. With the development of the myoblast into 

 the adult muscle fiber, this net becomes more and more complex. 

 In addition to this net there is formed a placque which I am 

 inclined, on morphological grounds, to regard as an intermediary 

 structure, which future work may identify as a receptor substance 

 similar to that occurring in motor endings. 



I wish to take occasion here to thank Dr. Florence R. Sabin 

 for the help which she so willingl}' gave me at various times 

 during this work. 



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