556 MAYNARD M. METCALF, 



This is the only reference he makes to the nature of the secretion 

 of either of the glands, except to describe the staining reactions of 

 the cells of their endothelia. 



Of the two glands which compose the so-called hypophysis of 

 Vertebrates, the one derived from the central nervous system, namely 

 the infundibular gland, does not now open to the pharynx, nor is 

 there any evidence that it has ever done so. The anterior part of 

 the central neural tube can hardly be said to function as its duct, 

 nor the neuropore as the aperture of its duct. Such an interpretation 

 would be rather far-fetched. Amphioxus, in which the infundibulum 

 and neuropore are both present, shows no neural gland at all. The 

 only indications of an homology between the infundibular gland of 

 Vertebrates and the neural gland of Tunicates would be the position 

 of both below the anterior end of the central nerve tube and the 

 origin of both from this tube. 



The other part of the so-called hypophysis, the true hypophysis, 

 does not arise from the central nervous system, the anterior part of 

 the central nerve tube never functions as its duct, nor the neuropore 

 as the aperture of its duct. The origin of this gland from the ecto- 

 derm of the stomodaeum may indicate that formerly it opened into 

 the stomodaeum. I see no sufficient indication that such an opening 

 into the stomodaeum, if ever present, should be regarded as the 

 modified neuropore, or the duct leading to it, as the anterior end of 

 the neural tube. It is possible to conceive that such were the former 

 relations, but I see no indication of the probable correctness of such 

 a surmise. Certainly the present opening of the hypophysis within 

 the skull is secondary. The granular mass of detritus in the lumina 

 of the tubules of the hypophysis, to which Haller makes casual 

 reference, shows that at least a portion of this gland in the Selachians 

 (and, if here, probably in other forms also) forms its secretion in the 

 same way as does the Tunicate neural gland. 



The only grounds for horaologizing the hypophysis of Vertebrates 

 with the neural gland of the T u n i c a t a, seem, then, to be the position 

 of both near (usually below) the anterior end of the central nerve 

 tube, the similarity in the manner of forming the secretion in the 

 neural gland and in the hypophysis proper, and the fact that the 

 Tunicate neural gland and one of the two glands composing that which 

 has commonly been called the hypophysis in Vertebrates both arise 

 from the neural tube. Yet, though this evidence seems insufficient, 

 I confess to a feeling that this very attractive supposed homology 



