ASTERIAS PALLIDA. 



251 



The portion of the intestine that remains connected with the stomach 

 is taken in in the formation of the stomach of the adult. 



Fcrmancnt (jut. — From the above description it is clear that the 

 larger part of the larval gut enters into the formation of the permanent 

 gut. The intestine hangs on to the stomach for a while hut little chang- 

 ed \\\ form, hut in stage H it can not be recognised as such. The œsoph- 

 agus, however, is never completely incorporated with the stomach but 

 always projects more or less orad. In stage E (Fig. 10) the stomach 

 is already seen to send out indistinct diverticula into the rudiments of 

 the arms. These diverticula grow into the arms as these are developed; 

 they are at first simple, but in a star wdiose radius is 2.5 mm. they 

 are distinctly double. In this young star the rectal vesicle as well as 

 the metaproct is already developed. The former is at this stage an 

 irregularly ovoidal sac situated in the right dorsal interradius, but 

 extending more into the base of the right ventral arm, and is connected 

 with the stomach by a short but distinct canal. Its aboral wall is 

 directly applied to the aboral disc, so that no free space is left between 

 the two. We shall afterwards see how this affects the schematic 

 arrangement of the body cavities. From the rectal vesicle proceeds 

 obliquely aborad a short rectum, which opens in the same interradius 

 as that in which the vesicle is situated, but near the centre of the disc, 

 as made out by Ludwig long ago ['80]. 



I call oesophagus that portion of the definitive gut which can be 

 evaginated outside the bod3\ This portion is composed of cells which 

 differ in character from those of the rest, these cells being slender 

 and cylindrical and closely set and with nucleus elongated oval, while 

 in the remaining portion of the gut, the hepatic cœca included, the 

 cells are mosthT- cubical and the nucleus spherical. It is perhaps 

 needless to remark that the hepatic cœca are connected with the aboral 

 end of the gut. 



