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Nachdruck verboten. 



Notes on Tunicate Morphology. 



By Matnard M. Metcalf, Ph. D., Assoc. Prof, of Biology, the Woman's 



College of Baltimore. 

 With 3 Figures. 



I. The „sub-neural" Gland in Ascidians. 



As usually described the sub-neural gland of Ascidians lies ven- 

 tral to the ganglion, being separated from the latter by the duct of 

 the gland, which opens anteriorly into the pharynx through the ciliated 

 funnel. The gland itself has been described in different species as a 

 compact tubular gland with its tubules more or less ramified (Clave- 

 lina [L. Sheldon]); or as a looser tubular gland (Phallusia mentula 

 [Julin]); or as a mere mass of much vacuolated cells (Amaroecium 

 [L. Sheldon]). The size of the gland may be considerable, as in 

 Clavelina and Amaroecium, or inconsiderable, as in Julinia. It may 

 have no apparent connection with the ganglion (Corella [Julin]), or 

 may be more or less fused with the latter (Julinia [Calman]). 



I have studied thusar Clavelina (sp. ?), Perophora viridis (Verrill), 

 Amaroecium stellatum (Verrill), Botryllus Gouldii (Verrill), Molgula 

 Manhattensis (Verrill), Cynthia partita (Stimpson) and Boltenia 

 Bolteni (L.) ; and in these forms I find very cousiderable differences. 

 In Clavelina, Perophora and Amaroecium the gland is in the condition 

 usually described for the Ascidians. In Botryllus, Molgula, Cynthia 

 and Boltenia the gland is dorsal to the ganglion. The degree of 

 development of the gland is different in the different species and its 

 histology varies considerably. In Molgula the gland is very loose 

 and diffuse. In Cynthia it is fairly compact. In Boltenia the duct 

 is very much enlarged: the cells of its lining epithelium proliferate: 

 the resulting cells drop into the lumen which is more or less filled 

 by them. Presumably these cells degenerate to form the secretion of 

 the gland, though in my material, preserved in formalin, I was unable 

 to study their intimate structure, to see if they were actually degene- 

 rating. In the neural gland of Boltenia there are no tubules nor is 

 there any mass of vacuolated cells connected with the enlarged duct 

 which is itself the whole of the gland. 



The condition of the gland in Botryllus is shown in the accom- 



