TKOCHOPHOEE OF EYDROIDES ITNCINATUS (kUPOMAITs). 565 



but those obtained from tlie body-cavity are always flattened 

 and lenticular in shape. On being- placed in sea-water, after 

 a short time they fill out and become spherical and regular 

 in outline. They are covered by a thin membrane which 

 remains attached throughout segmentation nnd gastrulation, 



Text-fig. 20. 



stTue 



coe. 



■mcsc. 



- ~- a-a.V. 



Sectiou through a troeliophore of Eiipomatus three days old. 

 an.v. Anal vesicle, ixe.m. Coelomesoblast. hli. Head-kidney. 

 stmc. Stomach. 



becoming the cuticle of the trochophore. This in the living- 

 egg is smooth and transparent, but shrinks and becomes con- 

 siderably wrinkled under the reaction of rengents, especially 

 sublimate. This renders tlie study of fixed material difficult, 

 as the cuticle has a strong afiinity for stains, obscuring the 

 underlying cells and adding- to the uncertainty of orientation. 



