1 6 4 



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 



2>e7?Ej£firi 



Fig. 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 F) and ampullae {Amp) 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, 

 ampullar; an, anus; C. Amb. I', circular ambulacral vessel; C. B. V, septum 

 of ring blood-vessel; Cd. c&, cardiac caeca; Ctel, ccelome; Coel. Epiihm, 

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

 Epthm, enteric epithelium; Int. ctz, intestinal cxca; Mdpr, madreporite; Mes, 

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

 ovd, oviduct; Fed, pedicel^n^:; pk, perihaemal spaces; Pyl. ceec, pyloric caeca; 

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

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

 stomach; St. c, stone-canal; /, 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 



