HISTOLOGY AND DEVELOPMENT OF MYBIOTHELA PHEYGIA. 523 



under the name of " nutritive spheres/^ The vacuolate cells 

 of Myriothela wheu free from nutritive spheres may be seen 

 to possess a large vacuole surrounded by scanty protoplasm. 

 In this condition they recall the palisade-cells of the oral 

 region, and the intermediate types are so numerous that I 

 am disposed to regard these cells as fundamentally the same. 

 The most constant differences are that the palisade- cells have 

 almost always twin nuclei, and only rarely contain nutritive 

 spheres. 



Wedged here and there between the vacuolate cells are 

 other and smaller dark-staining cells (fig. 21), which occupy 

 the same postion but are not disposed with the same regu- 

 larity as the goblet-cells. These cells are as variable in 

 size and appearance as the vacuolate cells, and they correspond 

 to the " gland-cells " of Nussbaum and Jickeli. Miss Green- 

 wood has shown reasons for considering that cells similar 

 to these occurring in the endoderm of Hydra are concerned in 

 the formation of the digestive enzymes, and I find that her con- 

 clusions are warranted by the different appearances presented 

 by these cells under varying conditions in Myriothela To 

 this point we will return later. 



Rarely a gland-cell may be seen apparently bearing a deli- 

 cate pseudopodium or flagellum, and having the appearance 

 shown in fig. 186. Nussbaum similarly describes cilia on the 

 gland- cells of Hydra. 



These gland-cells are very widely dispersed throughout the 

 endoderm. They occur, perhaps, in greatest abundance on the 

 sides of the villi ; sometimes, however, one or two may occur 

 at the apex of a villus. Rarely, at the apex of a villus, a group 

 of two, three, or four small cubical darkly-staining cells is 

 found (fig. 19). Whether these are or are not stages in the 

 development or multiplication of gland-cells I was unable to 

 determine. That they are, however, the antecedents of the 

 free corpuscles which at certain periods occur in the somatic 

 fluid I see no reason to doubt. 



The gland-cells of Myriothela have a rather wider distri- 

 bution than those of Hydra, where they are restricted to the 



