554 MAYNAED M. METCALP, 



a little negative evidence. The reaction of the gland cells to haemato- 

 xylin staining indicates that this is not a mucous gland , as Roule 

 believes 1). The manner of forming its secretion, like a sebaceous 

 gland, by disintegration of cells proliferated from its endothelium, is 

 not such as to suggest a renal function-). The only reasoning I 

 know, which might lead to the usual assumption that the neural 

 gland is renal, is that, as most Tunicata are not known to have any 

 other renal organ, this gland must have this function. This is hardly 

 sufficient proof. 



Roule ^) believes that the substance secreted by the neural gland 

 is poured out by the funnel into the branchial chamber, serving to 

 catch the particles brought in by the water, in order that they may 

 be carried along the dorsal lamina to the oesophagus. This is the 

 function Fol'*) has so clearly demonstrated for the endostyle and 

 peripharyngeal bands and it would hardly seem necessary that there 

 should be another large gland for the same purpose. The opening of 

 the accessory ducts into the cloaca in certain simple Ascidians would 

 argue against such a function. One other slight indication can be 

 noticed. The groove in the dorsal lamina is usually filled with 

 particles caught in a slimy fluid similar to that secreted by the endo- 

 style ; while, on the other hand, one seldom finds any slime or secretion 

 of any sort in the ciliated funnel, 



I have carefully studied through all my sections with the pur- 

 pose of determining if the neural gland may be a lymph gland or 

 may be a place of formation of leucocytes. The staining reactions 

 of the cells within the gland as compared with those of the blood 

 corpuscles preclude this interpretation. In one case I have found 

 blood corpuscles within the gland, i. e. in BoUenia, and in another 

 case, Salpa cylindrica, which has no gland connected with the funnel, 

 I found blood corpuscles in the upper, non-ciliated part of the funnel. 

 Herdman describes a very peculiar gland of an undetermined species 

 in which the connective tissue sheath of the gland invades its lumen 

 in the form of trabeculae which hold in their meshes the cells pro- 

 liferated from the endothelium of the gland •^). Similar trabeculae, 



1) RouLE, 1886, p. 102. 



2) Cf. JuLiN, 1881, second Paper. Kowalevsky's studies of the 

 neural gland would indicate that it probably is not renal. 



3) RouLB, loc. cit. 



4) Fol, 1874. 



5) Hebdman, 1888, the last appendix to Part 3. 



