520 W. B. HARDY. 



retracts this region to such an extent that the epithelium is 

 thrown into deep folds^ and the free surfaces of the cells ap- 

 posed. This ciliated zone forms only a narrow band. Between 

 the bases of the ciliated cells are (2) numerous rounded and 

 deeply-staining cells^ which are more numerous the nearer the 

 lip. Delicate processes may be sometimes seen passing from 

 them to the surface, and they are probably sense-cells. Below 

 these, and forming by far the greater portion of the epithe- 

 lium, are strikingly characteristic palisade-like cells. Each 

 has a very scanty and ill-stainiug protoplasm, which surrounds 

 a large irregular vacuole occupying the bulk of the cell. Two 

 nuclei, each with a small nucleolus, are usually present, and 

 may be either close together about the middle of the cell, or 

 one at either end. There is not the slightest evidence that 

 the presence of these twin nuclei indicates cell division. 



At the lower edge of the ciliated zone conical cells appear 

 between and rapidly replace the ciliated cells, while at the 

 same time the deep-staining sense-cells disappear. Each of 

 these conical cells resembles in its general appearance a goblet- 

 cell of an ordinary mucous membrane. We can, therefore, 

 conveniently style the next region the goblet-cell zone. 

 This embraces a considerable portion of the tentacle-bearing 

 region. It is, however, impossible to reduce the relative 

 dimensions of these various zones to numerical exactness 

 because of the extreme extensibility of this portion of the 

 animal. 



Each goblet-cell is, as its name implies, flask-shaped, and 

 consists of an expanded part which stains lightly with picro- 

 carmine (fig. 16) or osmic acid (fig. 15). The contents 

 of this part are turbid from the presence of ill-defined, 

 granular masses. The expanded portion of the flask is 

 continued downwards into a tail, which contains a small 

 nucleus embedded in deeply-staining granular protoplasm. 

 The numerous and coarse granules of the basal portion stain 

 deeply with osmic acid, and less so with picro-carmiue. These 

 cells are undoubtedly of the nature of gland-cells, and the well- 

 formed basal granules may be regarded as the first stage in 



