Notes on the morphology of the Tunicata. 553 



the character of the water which passes through the pharynx. This 

 guess may be as good as any other. I would, however, make one 

 suggestion. The fact that in four different Ascidians (Ascidia atra, 

 Ascidia marioni, Phallusia mammillata and Polycarpa sulcata) the 

 lateral branches of the duct open to the pharynx or cloaca by ciliated 

 funnels similar to that by which the main duct opens, seems to imply 

 that the function of these funnels, whatever it may be, is, in part at 

 least, associated with the gland. No sensory function has been shown 

 for these accessory funnels and their relation to the gland may not 

 be of a sensory nature. On the other hand, the fact that the ciliated 

 funnel in the Salpidae and in the Phorozooid of Doliolum affine has 

 no connection with the gland shows that the sensory function of the 

 funnel, whatever it may be, is at least not exclusively in relation to 

 the gland ^). 



The Neural Gland-). 



In endeavoring to learn the present function and ancestral history 

 of the neural gland of Tunicates and its homologies with structures 

 in other groups, there are certain salient features to be remembered. 

 It lies near to and is derived from the central neural tube. Its duct 

 is the anterior portion of the neural tube and this still opens by the 

 (modified) neuropore to the pharynx. Its secretion is formed by the 

 disintegration of cells proliferated from the endothelium of its wall. 

 The gland is very différent in different species in its degree of devel- 

 opment and in the character of its rapheal prolongation, but there 

 is no great variability within the limits of a single species. 



With these salient points in mind, naturally the first question is: 

 "What is the function of the neural gland?" I have obtained no 

 results that enabled us to answer this question. I have not attempted 

 chemical tests of the nature of the secretion ^^). There is, however. 



1) An olfactory function has been assigned to the pit in Amphioxus, 

 which, like the ciliated funnel of Tunicates, is but the modified neuro- 

 pore. I do not know that any such function has been attributed to 

 the "neuropore" of Balanoglossus. It seems hardlj' fair that in the 

 distribution of honors Balanoglossus should be so slighted. 



2) The term "sub-neural gland", which is in frequent use, is, of 

 course, inapplicable to the Tunicates as a whole. 



3) It would be a comparatively easy matter to dissect out a suf- 

 ficient quantity of the glandular tissue from certain species to make 

 chemical tests. Molgula manhatiensis, whose gland is of large size, 

 would be a good form upon which to work. 



