I10 ROBERT H. BOWEN*. 



evolution in the first weeks after birth. This at least suggests 

 the possibility that in other nerve cells the adult arrangement ot 

 the Golgi material may likewise be a product of post-embryonic 

 development depending of course in detail upon the kind of 

 cell and its time of functioning with respect to birth, etc. 



I have digressed here into these details of the differentiation 

 of the Golgi network because of their remarkable connection 

 with the relations recently developed by Tilney, between the 

 beginning of functional activity of a given muscle and the time 

 of myelini/ation of the corresponding nerve tracts. It would 

 appear that the nerve fiber is not the only part of the mechanism 

 which at birth is still in an incomplete state, but that the muscle 

 fiber and possibly also the nerve cell itself have still to perfect 

 their organization subsequent to birth. Here the agreement in 

 the guinea-pig between the completion of myelinization before 

 birth as noted by Tilney and the perfection of the muscle net- 

 work as noted by Yeratti, with the known activity of the new- 

 born young of this animal, seems to me of extraordinary interest. 

 It thus appears that the failure of the nerve-muscle mechanism 

 to operate immediately after birth may be due not only to the 

 lack of the myelin sheaths but to the fact that the system as a 

 whole is still in process of completion. 



The possible relation of this muscle reticulum to the Golgi 

 apparatus was first discussed by Yeratti, who refrained from 

 drawing any definite conclusion. Sanchez ('07), however, con- 

 cluded that this network represents the apparatus of Golgi- 

 Holmgren, and though he had in mind Holmgren's conception 

 of a trophospongium, it is equally clear that he intended an 

 homology with the Golgi apparatus as conceived by other workers. 

 At about the same time Holmgren ('08) published an account of 

 the network in many kinds of muscle cells, and endeavored to 

 prove that it represented the trophospongium described by him 

 in other kinds of tissue. Golgi himself seems to have accepted 

 the homology of the muscle reticulum with his 'internal reticular 

 apparatus.' In his ivview of i<)ii, Duesberg considered the 

 case unproved, but in i<M4 lie states that "the hypothesis of 

 Golgi is probably correct." The only obvious criticism of this 



1 The not very convincing account and figures of Luna ('n) on mammalian heart 

 muscle must thus be considered as probably incorrect. 



