il GEORGE L. STREETER 



speaks of the endolymphatic appendage as a tube extending from 

 the labyrinth to the cranial cavity where it either ends blindl}^ 

 as an 'epicerebral lymph space' or opens into the general epicere- 

 bral lymph space (p. 768). Elsewhere (p. 792) he describes a 

 small funnel-shape flaring process of the endolymphatic sac that 

 penetrates through a small opening in the dura and there fuses 

 with the arachnoid, thus establishing a communication between 

 the 'cavum endolymphaticum' and the 'cavum epicerebrale.' 

 The function of the endolymphatic appendage, according to 

 Hasse, is threefold: 1, the sac, during embryonal life, is an epi- 

 thelial secretory organ that furnishes the endolj^mph; 2, in the 

 adult, it is either a closed sac that secures new materials for the 

 endolymph by endosmosis from the epicerebral spaces, or it is 

 an open sac through which the epicerebral fluid flows directly 

 into the chambers of the labyrinth; 3, the endolymphatic sac is a 

 reservoir for endolymph which serves as an expansion tank that 

 relieves the pressure when it becomes too great in the labyrinth. 



The investigators who have studied the blood supply of the 

 labyrinth do not seem to have directed much attention to the 

 vascularization of the endolymphatic appendage. They have 

 done little more than to confirm the observation of Cotugno, 

 made a century and one half ago, that a vein draining the vesti- 

 bule and the canals accompanies the endolymphatic duct and 

 empties into one of the dural sinuses. The most careful descrip- 

 tion is that of Siebenmann '94 who showed, as others had done 

 for the aquaeductus cochleae, that the veins of the vestibular 

 aqueduct (endolymphatic appendage) though originally accom- 

 panying the duct, become separated later in their own bony 

 canal, which he designated as the 'canalis accessorius aquae- 

 ductus vestibuli.' Eichler '92 who studied the blood-vessels of the 

 human labyrinth confined his attention to the cochlea. 



Shambaugh '03 describes the endolymphatic duct as incased by 

 capillaries which are supplied by an arteriole coming usually from 

 the posterior vestibular artery, and are drained bj^ a vein that 

 empties into the transverse vestibular vein. Where the endo- 

 lymphatic sac was preserved it was found to be drained b}' a 

 small dural vein. 



