GOLGI APPARATUS IN STRIATED MUSCLE. 113 



Assuming that the Cajal-Fusari reticulum actually is the Golgi 

 apparatus of a striated muscle fiber, there is raised at once the 

 interesting question of the functional relation of this material 

 to the functional activity of the muscle itself. It was thought 

 by Cajal that the network, in the insect muscle upon which he 

 worked, was in one sense or another a continuation of the tracheal 

 network. This view was supported by Sanchez ('07), and 

 elaborately developed by Holmgren ('08), who found in the 

 network the trophospongium of his familiar hypothesis. Ac- 

 cording to Holmgren, in insects this network is in reality a 

 protoplasmic extension of tracheal end cells located on the 

 surface of the muscle fibers; while in vertebrates (and other 

 forms where tracheal tubes are lacking) it is a similar extension 

 of materials essentially to be related to the sarcolemma, or 

 " trophocy tes " connected with it. To most workers this would 

 probably seem a very perilous expedient for saving the homolo- 

 gous nature of these networks, especially in view of the fact that 

 the trophospongium in many kinds of cells has been shown to be 

 the Golgi apparatus pure and simple, and quite lacking in its 

 supposed relationship to external trophic cells. As a matter of 

 fact, the supposed relation of the network to the tracheal tubes 

 in insect muscle fibers was investigated and discussed by Veratti, 

 who denied the connection described by Cajal (and later Holm- 

 gren). To me the evidence seems to indicate that the networks 

 are essentially independent of extra-muscular formations, but 

 that possibly in insects, tracheal endings may be closely associated 

 with the fibers of the network in a purely spatial sense. While 

 therefore rejecting Holmgren's theory, it is nevertheless inter- 

 esting to note further that he found in this network an area of 

 metabolic transformations comparable to that of the tropho- 

 spongium in other cells. 



Bearing in mind these facts of morphology and supposed 

 functional significance, it has proved interesting to me to con- 

 sider the problem in the light of the recent development of 

 opinion on the role of the Golgi apparatus in cells generally. 

 From this it begins to appear that the Golgi apparatus is very 

 generally involved in the synthetic operations leading to the 

 formation of various secretory products, including many extra- 



