98 LECTURE VIII. 



tentacular cilia appears under the control of the animal, and they are 

 sometimes seen completely at rest. The arms are tubular throughout, 

 and have an aperture at each extremity. The ring upon which they 

 are set forms a projecting edge around the mouth. The particles of 

 food are carried down the inner surface of each arm, and the mouth 

 and pharynx expands to receive such as are appropriate, as if by an 

 act of selection. The rejected particles pass out between the bases 

 of the tentacula, or are driven off by the centrifugal currents. 



The pharynx (^fig. 51, /) is less dilatable than the mouth of the 

 Hydra or Actinia. The constriction of the pharynx, by which the 

 food is driven into the oesophagus, is a very well-marked action. 

 The cardiac orifice (</) seems to project into the oesophagus upon a val- 

 vular prominence ; it opens into a small globular cavity (Ji), which has 

 the construction of a gizzard : the interior of this cavity is lined 

 by a strong epithelium, the cells of which project into the cavity like 

 pointed teeth, and the food is subject to comminution in this cavity. 

 With the gizzard is associated, as in birds, a distinct glandular com- 

 partment of the stomach {%) ; but this is situated between the gizzard 

 and intestine, not between the gizzard and oesophagus : its walls are 

 studded with follicles filled with a rich brown secretion, which may 

 be regarded as hepatic follicles. The intestine is continued from a 

 distinct pyloric orifice (A), which is situated at the upper part of the 

 glandular stomach near the gizzard. This orifice is surrounded by 

 vibratile cilia. The food is frequently regurgitated into the giz- 

 zard, and, after having undergone additional comminution, is returned 

 to the stomach. Hei"e it is kept in constant agitation, and the par- 

 ticles pass by a rotatory action from the pylorus into the intestine. 

 The indigestible particles are there formed into little pellets, which 

 are carried rapidly upwards to the anal orifice (/), and, after being 

 expelled, are immediately whirled away in the current produced by 

 the ciliated tentacula. 



A small filament, conjectured to be tubular, which passed from the 

 base of the glandular stomach to the common stem (w) supporting the 

 cell of the polyjie, is the only trace of the nutrient or vascular system 

 which Dr. Farre could detect. When the common stem of a 

 ramified Bryozoon is cut across, it seems to be nearly homogeneous, and 

 does not present that obvious distinction between hard and soft parts, 

 nor the canal with circulating particles, which are observed in the 

 stems of the compound Hydrozoa. Yet it can scarcely be doubted 

 but that nutrient currents inust traverse the common connecting 

 organic medium or stem of the Bryozoa, both for its own support and 

 growth, and for the supply of the means of growth to the young 

 animals (C) which are developed from it by the process of gemmation. 



