00 EENES'L' WAEKEN. 



cavity of the canals, roofed over by thin branching cells, 

 expands considerably, and in the region of the perisarc 

 groove these coverings of thin cells come into close contact 

 and constitute some nine to twelve radial septa (fig. 13, v. s.). 

 The cells in contact with the mesoglea do not appear columnar 

 in fig. 13 ed. owing to the fact that the cells, hanging down 

 from the diaphragm (fig. 5 ed.), are cut obliquely. The endo- 

 dermal canals (e. c.) open into the vesicular endoderm of the 

 hydranth by irregular channels, which pass round the edge of 

 the diaphragm-pore (fig. 5, o. e. c). Bodies similar to those 

 seen in the endoderm cells of the floor of the hydranth (figs. 5 

 and 5 a,pr.) can be observed in the hydrocaulus (fig. 13, g. m., 

 and fig. 5, j>r.). 



The endodermal canals probably serve to convey nu^tritive 

 fluids. It must be remarked that cilia were not clearly seen 

 on the columnar cells, although the specimens were carefully 

 fixed. ^ The general histological condition of the sections was 

 very good. I believe, however, that cilia or flagella are 

 present, whicli are of too delicate a nature to remain clearly 

 visible after the ordinary processes of fixation and imbedding, 

 etc. In some of the specimens examined the columnar cells 

 of the endodermal canals contained a considerable number 

 of globules similar to those which are so abundant in the 

 endoderm of the tuber-like expansions of the hydrorhiza. 

 Towards the base of the hydrocaulus the endodermal canals 

 gradually fuse together and constitute a regular layer of 

 columnar epithelium, and the canals, as such, disappear. As 

 the tuber-like expansions are approached, the endoderm cells 

 become taller and more crowded with globules. Fig. 16 is a 

 small piece of a transverse section of a tuber. Here the endo- 

 derm is so tall that the lumen of the tuber is almost obliterated. 

 The cells are densely crowded with fairly large globules of a 

 wonderfully uniform size. The globules appear perfectly homo- 

 geneous, and without doubt consist of reserve food material. 



' Fixation was accomplished hy (1), Flemming's solution, six hours ; 

 (2), half concentrated corrosive sublimate in 30 per cent, spirit and 

 \l per cent, acetic acid, applied hot. 



