13 GUSTAV EISEN: PON fOSCOl E X 



ganglia arc situated on the outside of the cell wall, though in :. dis- 



appears as if at least part of the fibres were inside the cell. II . with - 



small objects, this is not easy to determine with certainty, anil until I can pro« 

 new specimens fixed with osmic acid, etc., for the sp I hold that 



these supposed ganglionic cells only spread on the surf; cell without 



penetrating the walls. My reason for considering them to be either ganglia or 

 nerve endings is simply that I can not very well see how they could be any thing 

 else. In carefully focussing on the surface of the cell I can clearly see a rov 

 these branching dark-staining bodies continuing all around the cell wall. There are at 

 least always four of them, regularly arranged near and around th< of the etil, 



in line with the upper edge of the floor; but sometimes there i- also a row of them 

 higher up, as in fig. it, n. e., and in one or two instances there w< r also al 



the cap in line with the reflexed fibers and plates of the lower funnel. At the- b 

 of the cell and outside of each I can distinguish numerous nerve fibers leading 

 wards the central nerve ganglion (fig. 8, n. f.). In figure 8 may also I . similar 



ganglionic plates on the wall of the unicellular gland to the left of the sense cell. '1 

 are here also found at the base, and on the outside of the wall, and sonv of their 

 fibers or cell prolongations reach over to the next cells to the left. It will thus be 

 seen that these ganglia or nerve endings are not peculiar to the sense cells, but 

 exist elsewhere; but they certainly are larger, more regular on the sense cells than 

 on the gland cells. In some instances I have seen a nucleus at the supposed gang- 

 lion, but I am uncertain if it really belonged to it or not. 



The question now arises, what is the nature of this peculiar and highly differ- 

 entiated cell? As Horst has shown, Beddard's opinion that we here have a bristle 

 cell, is not tenable. Nor is there any resemblance either with the unicellular glands, 

 with the supporting cells, or with the ordinary sense cells found in the epidermi 

 all higher oligochtetae, and which have been described by several investigators and 

 by myself lately in Benhamia and Aleodrilus. Horst's suggestion that we here have 

 to do with a sense cell is the only one which I consider worthy of consideration. 

 The constant and complex arrangement of the cytoplasm and the peculiar globular 

 body in the upper funnel speaks for some unusual function, not generally found in 

 single cells. This globule impresses me as being a kind of otolith; i il is not 



of a refractive or stony nature, as I propose to call it, an otosome. I believe in fact 

 that we here have an organ of hearing, and that the otosome serves as an otolith. 

 The cell seems especially constructed so as to korp this otosome in place, confined 

 to the upper vacuole, while the beautiful protoplasmic structure below it might serve 

 to propagate the sound waves to the nerve.- below. The central cytopla« 



