INTRODUCTION. 



to which external impressions can be transmitted, or nervous 

 filaments calculated to conduct sensations to distant points 

 of the system, or associate muscular movements, they are 

 necessarily incapable of possessing those organs which are 

 dependent upon such circumstances: instruments of the ex- 

 ternal senses are therefore totally wanting, or their existence 

 is at least extremely doubtful ; the contractile molecules of 

 their bodies are not as yet aggregated into muscular fibre. 

 The alimentary apparatus consists of canals or cavities, per- 

 meating the parenchyma of the body, but without distinct 

 walls, as in the higher divisions, where it floats in an abdom- 

 inal cavity. The vascular system, where at all perceptible, 

 consists of reticulate channels, in which the nutrient fluids 

 move by a kind of cyclosis. Their mode of reproduction is 

 likewise conformable to the diffused state of the nervous and 

 muscular systems ; not only are most of them susceptible of 

 being multiplied by mechanical division, but they generate 

 by spontaneous fissure, as well as by gemmae, ciliated gem- 

 mules, and true ova. Many appear to be made up of a repeti- 

 tion of similar parts, forming compound animals of various 

 forms, and different degrees of complexity. 



The only animal substance yielding a medicinal agent ob- 

 tained from this Division of the animal world is from 



Class 5. The Spongia. 



SPONGIA OFFICINALIS, the Sponge. The No. 1 of this work. 

 Isis NOBILIS, the Coral, is now rejected from the list of the 

 Materia Medica, and forms no No. of this work.* 



* Isis NOBILIS, the Coral. A substance found at the bottom of the Mediterra- 

 nean and other seas, formerly considered as a plant, but now universally admitted 

 to belong to the animal kingdom. The red coral (Corallium rubrum of Lamarck, 

 Isis nobilis of Linn.) is in the form of a small shrub, a foot or two in height, with a 

 stem sometimes an inch or two in thickness, fixed to the rock by an expansion of 

 the base, divided above into branches, and covered with a pulpy membrane, which 

 is properly the living part, and which is removed when the coral is collected. The 

 central portion is extremely hard, of various shades of red, susceptible of a brilliant 

 polish, longitudinally striated, and formed of concentric layers, which are rendered 

 obvious by calcination. Its chief constituent is carbonate of lime, which is colored 

 by oxide of iron, and united, as in similar calcareous products, with more or less 

 animal matter. It was formerly very highly valued as a remedy, but is in no 

 respect superior to prepared oyster-shell, or other forms of carbonate of lime, de- 

 rived from the animal kingdom. It was employed in the form of tine powder, or 

 in different preparations, such as troches, sirups, conserves, tinctures, &c. At pres- 

 ent it is valued chiefly as an ornament. 





