374. DEXDKITIC APPENDAGE OF UROGENITAL PAPILLA 



bottom of the pltis overlying the glandular cells, and he was at a loss 

 to account for the way by which the secretory product of the glandular 

 cells was discharged into the cavity of the pits. He supposed that 

 the condition found in his sections was due to the fact of his speci- 

 mens being immature, and that in the adult, the epidermal cells were 

 removed from the bottom of the pits, thus exposing the glandular 

 cells. This statement is somewhat remarkable, as even in specimens 

 much younger than those studied by him, the glandular cells are freely 

 exposed at the bottom of the pits, as I have stated above (see Figs. H 

 and 22). It is possible that his sections were cut somewhat obliquely 

 and thus failed to show the true state of things. The glandular cells 

 are also stated by J^rock to form a continuous layer, whereas in reality 

 every group is discontinuous from the adjacent ones. 



The Cormm, 



The inner zone of the dendritic appendage consists of smooth 

 muscular fibres containing nerves, large blood vessels, and irregularly 

 branched lymph-cavities. From sections we learn that this inner zone 

 attenuates in thickness from the stalk towards the tips of the lobes. 

 In the latter position, it is thicker in the middle than towards the 

 edges. In longitudinal sections of the biisal portion of the stalk, 

 showing the connection between the appendage and the body proper 

 (Fig. 18), we observe that the peripheral ])art of the muscular zone is 

 directly continuous with the C'^rium of the body proper, while the 

 middle part runs deeply inwards to attach itself to the ventral 

 apophyses of the vertebras, mainly to those of the second and third 

 caudal vertebrœ and partly to those of the first '^ and fourth. 



lîlood is supplied to this appendage by a pair of arteries which 



1) I desicfnate the first vertebra which forms the haemal arch by a bony bar the first caudal 

 vertebra. It is perhaps the third according to Brock's nomenclature. 



