Notes on the morphology of the Tunicata. 499 



the branches of the gland are lined by cubical epithelium similar to 

 the endothelium of the duct. These cells are in active proliferation ^). 

 The products of their division, dropping into the lumen of the gland, 

 completely fill it with a mass of lightly staining degenerating cells. 

 The secretion of the gland is the product of the degeneration of these 

 cells 2). This is much more easily seen in other species where the 

 mass of cells is not so great, and crowding does not obscure the 

 true relations. (Cf. BoUenia reniformis, page 512, Plate 35, Fig. 20, 

 and Cynthia papulosa^ page 599, Plate 35, Fig. 16.) I have already 

 called attention to the great blood sinus surrounding the brain and 

 neural gland. The rich blood supply is probably of importance to 

 the gland. 



In connection with the study of other species evidence will be 

 presented that the ciliated funnel is not merely the aperture of the 

 neural gland, but is associated with a sensory function^). The re- 

 lations are not so clear in Ciona, but it is worth mentioning that a 

 small mass of medium-sized ganglion cells, connected by nerve fibres 

 with the brain, lies upon the dorsal wall of the duct, between the 

 brain and ciliated funnel. The basement membrane of the duct is 

 somewhat interrupted here, and the outer ends of its endothelial cells 

 are irregular. For a much clearer demonstration of similar relations, 

 see the description of BoUenia reniformis (page 514 and Text-Fig. F, 

 also Plate 35, Figs. 19 and 21). 



The conditions in Ciona teneJla (Stimpson) and Ciona fascicu- 

 laris (Hanc.) are so similar as to need no separate description. I 

 have not sectioned Ciona flemingi (Herdm.), but dissected specimens 

 show relations practically identical with the other Cionas studied. 



Summary. 



Important facts mentioned in the foregoing de- 

 scription. 



1) Apparently by amitotic division, for I have never been able to 

 demonstrate mitosis in these cells in any species studied. 



2) The degeneration of these cells is not very rapid, the majority 

 of them being still intact as seen in sections of the gland of this and 

 other species. 



3) HuNTEK, at my suggestion, undertook a study of this and other 

 points of innervation, by means of methyl blue and gold chloride. In 

 a preliminary paper already published he records the demonstration of 

 sensory cells in the funnel. Cf Huntek, 18982. 



