• 1237 



whether there is a motor double innervation or a double innerva- 

 tion by means of a motor and a sympathetic terminal plate. This 

 point will be discussed at greater length in a future and more 

 detailed account. 



Sunmiaiy. 



All the spinal nerves, whose ventral ramifications form the plexus 

 brachial is, have in some cats been cut off between the spinal ganglion 

 and the place where the ramus commnnicans albus goes otf. \^hen 

 from five to ten days had elapsed after the operation, the animals 

 were killed. In sections of Ag. -impregnated mm. interossei from the 

 anterior extremity on the side operated on 1 found that all the 

 nerve fibres that had medullary sheaths were degenerated, but that 

 there were fairly numerous intact nerve fibres without medullary 

 sheaths. On account of the operations the animals had undergone 

 and the existing period of degeneration in the spinal nerves that 

 had been cut off I have reason to believe that these intact non 

 medullated nerves are of a sympathetic and post-ganglionar nature. 

 We are thus faced by the exceedingly interesting fact that the cross- 

 striated muscle fibres, even in the muscles of the extremity, are 

 innervated by n. sympathicus — corresponding to what Bokke showed 

 morphologically to be the case for the inner orbital muscles (m. 

 obliquus oculi superior). These sympathetic nerves in the extremity 

 musculature terminate in comparatively simple loop - formations 

 partly (among otliei- places) on ordinary cross-striated muscle fibres 

 and partly on muscle fibi'es in the muscle spindles. I have reason 

 to believe that the great majority of these sympathetic terminal 

 plates — both on ordinary muscle fibres as well as on those in the 

 muscle spinalles - — are situated hypo-lemmally — just as Bokkf. 

 described them in, among other places, m. obliquus oculi sup. of the 

 cat. I have also, however, preparations which indicate that there 

 are also epilemmally situated sympathetic terminal plates in the 

 extremity-musculature. A number of the sympathetic terminal plates 

 on ordinary cross-striated muscle fibres are situated within the region 

 of extension of the motor plates, but the majority lie outside it. 

 Among the sympathetic terminal plates that are situated outside the 

 region of the motor plates I have exam files of some that have a 

 rather large extension on the muscle fibres and on account of 

 this, approach the motor terminal plates. 



80 

 Proceedings Royal Acad. Amsterdam, Vol. XXI. 



