266 J. H. ASHWORTH. 



found in all stages of flexion, some being practically straight, 

 while others are bent almost into a semicircle. Their action 

 probably serves to keep the liquid in the ccelenteron in slow 

 motion, thereby securing a more equal distribution of the 

 nutrient substances contained therein to the cells in their 

 vicinity. 



Many of the endoderm cells are provided with '^muscle 

 processes," but these processes are not numerous in the 

 pinnules and in the stem ; they are more numerous in the endo- 

 derm of the tentacles and of the free portion of the polyp. 

 The muscle-fibres (except those forming the retractors and 

 protractors) have a circular direction, and are similar to 

 those of Alcyonium. In Alcyonium, however, the endo- 

 derm cells of the tentacles do not possess muscle-fibres (Hick- 

 son, 1895, p. 376). 



In teased preparations the muscle- fibres of the ordinary 

 endoderm cells may be clearly seen (fig. 26). On looking at 

 the flagella-bearing cells in the same preparations, it is seen 

 that most of these cells bear at their inner ends two processes 

 which appear to be less stiflF than the muscle-fibres of the 

 ordinary endoderm cells, and which are never in a straight line 

 with each other, but are invariably bent more or less towards 

 each other (fig. 27). It is possible that these are the modified 

 muscle-fibres of the cell, as they appear to be homogeneous, 

 and, when treated with fuclisin or iron hsematoxylin, stain 

 similarly to, though rather less deeply than, the muscle pro- 

 cesses of ordinary endoderm cells. The bending inwards of the 

 two processes from the inner end of the cell causes them to 

 become rather more deeply embedded in the mesoglcea than 

 the muscle processes of the ordinary endoderm cells, and the 

 cell is therefore provided with a firmly fixed base upon which 

 the giant flagellum can work as on a fulcrum. 



It is worthy of note that throughout the whole of the 

 colony the muscle processes of the endoderm cells (except the 

 protractor and retractor muscles on the mesenteries) are 

 circular in direction, whereas the similar processes (where 

 present) of the ectoderm cells are longitudinal in direction. 



