Anatomy. — "The sympathetic innervation of the cross-striated 

 muscle fibres of vertebrates.'' Bj Prof. J. Boeke and Dr. J. G. 



DUSSER DE BaRENNE. 



(Gommuuicated in the meeting of January 22, 1919.) 



Some years ago one of us, partly in these proceedinp:s and in 

 the transactions of this Academy '), published a number of observations, 

 which tended to show that on the cross-striated muscle fibres of 

 reptiles, birds and mammals there existed, beside the usual motor 

 endplates, still a second set of hypolemmal nervous endorgans, very 

 fine and delicate, which are seen in BiKi.scHOWSKY-prepaiations as 

 very small neurofibrillar end-rings and small end-nets, lying on the 

 surface of the muscle-fibres at the end of fine non-medullated nerve- 

 filaments. These so-called "accessory" nerve-endings lie hypolem- 

 mally on the muscle-fibres embedded in the granular sarcoplasm of 

 the fibre, and in some cases are found in the same layer of granular 

 protoplasm which surrounds also the terminal ramifications of the 

 common motor end-organ ; in other cases they are found as separate 

 endings, lying embedded in a distinct layer of nucleated sarcoplasm 

 independent of the motor sole, but, as far as could be made out, 

 they always appear as hypolemmal structures. The non-medullated 

 nerves that have these end-organs attached to their terminal nerve- 

 ramifications, are seen running in bundles between the muscle-fibres, 

 remain amyelinic throughout their whole course, and seem to form 

 a distinct system of nerve-fibres, independent of the motor and 

 sensible nerves. These observations, and especially the amyelinic 

 structure of these nerve-fibres gave room for the supposition, that 

 this so-called "accessory innervation" (Boeke, 1909) is of a sympa- 

 thetic nature, and in this way the conclusion was drawn (Bokke, 

 1909, 1911) that the cross-striated muscle-fibres (the end-organs, 

 mentioned above, were found in the muscles of the tongue, the eye, 

 the iris, the back, the m. pectoralis, in the intercostal muscles, and 

 afterwards Aoyagi found the same structures in the muscle of the 

 diaphragm) are not only innervated by the spinal nerves, but also 

 by the sympathetic system. The function of this sympathetic inner- 



1) J. Boeke, Studiën zur Nervenregeneration I and II. Verhandelingen K. A. W. 

 Second series. Vol. 18 and 19. 



