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MANUAL OF ZOOLOGY 



glandular : they secrete a digestive fluid, and are therefore to 

 be looked upon as digestive glands. It is found by experi- 

 menting with this digestive fluid that it has an action on 



FlG. 88. — Diagrammatic sections of a starfish. A vertical section passing on the 

 right through a radius, on the left through an inter-radius. The off-side of the 

 ambulacral groove with the tube-feet (T. E) and ampullae (Arnp) are shown in 

 perspective. B, transverse section through an arm. The ectoderm is coarsely- 

 dotted, the nervous system finely dotted, the endoderm radially striated, the 

 mosoderm evenly shaded, the ossicles of the skeleton black, and the ccelomic 

 epithelium represented by a beaded line, amb.os, ambulacral ossicles; amp, 

 ampullse; an, anus; C. Amb. V, circular ambulacral vessel; C. B. V, septum 

 of ring blood-vessel; Cd. c<e, cardiac cseca; Ccel, ccelome; Cccl. Epithm, 

 ccelomic epithelium; Der. Epitli7n, deric epithelium; Derm, mesoderm; Ent. 

 Epthm, enteric epithelium; Int. cce, intestinal caeca; Mdpr, madreporite; Mes, 

 mesentery; Mth, mouth ; Nv. R, nerve ring; oc, eye; os, ossicles of body-wall ; 

 ovd, oviduct; Fed, pedicellariae; pit, perihaemal spaces; pyl. ccec, pyloric caeca; 

 Rad. amb. v, radial ambulacral vessel; Rad. B. V, points to septum in the 

 radial blood-vessel; Rad. Nv, radial nerve; Resp.ca?, dermal branchiae; St, 

 stomach; St. c, stone-canal; t, tentacle; T. F, tube-feet. (From Parker's 

 Biology.) 



food-matters similar to that exerted by the secretion of the 

 pancreas in the Vertebrata, converting starch into sugar, 

 proteids into peptones, and bringing about the emulsification 



