I K T 



235 



I D 



parenchyma ; the only alimentary 

 organ it contains being ramified 

 canals. 



INTO'RSION. ) A twisting or turning 



INTO'RTION. j in any particular di- 

 rection. A term used in botany 

 and conchology. 



I'lnjuN. (from inula.} A vegetable 

 product, resembling starch, ob- 

 tained from the roots of the Inula 

 Hellenium, or elacampane, by 

 boiling them in water. It was 

 thus named by Mr. Rose. 



INVE'RSION. (inversio, Lat.) Change 

 of order or position so that the 

 upper may be lower, or the lower 

 upper; the first last, or the last 

 first. In the order of superposition 

 of the different stratified rocks, 

 some strata may be wanting alto- 

 gether, but there will not be found 

 an inversion of the regular order 

 of superposition. 



INVE'RTEBRAL. (from in and verte- 

 bral.) Not possessing any vertebral 

 column, or hard bony tube for the 

 spinal cord, or medulla spinalis; 

 not having a back-bone. 



INVE'RTEBRATE. } All those animals 



INVE'RTEBRATED. ) are invertebrated 

 which are included in the three 

 great divisions, mollusca, or cyclo- 

 gangliata; articulata, or diplo- 

 neura ; and radiata, or cyclo-neura. 

 The other great division includes 

 the vertebrata, or spini-cerebrata. 

 In the cephalopodes, the invertebrate 

 form of the lower divisions is 

 beginning to be lost, and the verte- 

 brate form of that division, to 

 which man belongs, to appear. 

 The first of the true vertebrated 

 animals, is the class of fishes ; from 

 this class upwards, including pisces, 

 amphibia, reptilia, aves, and mam- 

 malia, all are vertebrated. Prom 

 the class Pisces downwards, in- 

 cluding cephalopoda, pteropoda, 

 gasteropoda, conchiphera, tunicata, 

 of the division mollusca ; Crustacea, 

 arachnida, insecta, myriapoda, an- 

 nelida, cirrhopoda, rotifera, entozoa, 



of the division articulata ; echino- 

 derma, acalepha, polypiphera, pori- 

 phera, polygastrica, of the division 

 radiata, all are invertebrated. There 

 is one remarkable distinction which 

 separates the vertebrated from the 

 invertebrated animals, namely, 

 that in the former, the muscles 

 have no external points of attach- 

 ment ; and in the latter, with a few 

 partial exceptions, no internal ones. 



INVE'RTED. (from inverto, inversus, 

 Lat.) Turned upside down ; 

 turned inwards ; placed in contrary 

 order to that which was before, or 

 which is usual. 



INVO'LTJCEL. A small or partial in- 

 volucre. 



INVOLU'CRE. j (involucrum, Lat. cut 



INVOLU'CRUM. } aliquid involvitur-) 



1. Any membranous covering. 



2. In botany, a species of calyx, 

 remote from the flower, and bearing 

 a great resemblance to bractese : 

 the involucre is composed of many 

 small leaves placed at the foot of 

 the general umbel ; in umbellifer- 

 ous plants, the involucre, accom- 

 panying the partial umbels, is 

 called the involucella. 



INVOLU'CRET. A small, imperfect, or 

 partial involucre, an involucel. 



INVOLUTE. |.(from involve, Lat. 



INVOLUTED, j 1. In botany, applied 

 to leaves, when the margins are 

 rolled inwards upon each other. 

 2. In conchology, where the exte- 

 rior lip is turned inwards at the 

 margin, as in all the cyprese. 



I'ODATE. A compound salt formed by 

 the combination of iodine, oxygen, 

 and a salifiable base ; as the iodates 

 of ammonia, soda, &c. 



I'ODIDE. A compound of iodine and 

 some metallic substance ; as iodide 

 of iron, iodide of lead, &c. Also a 

 compound of iodine with a simple 

 non-metallic substance. When io- 

 dine combines with metals in more 

 than one proportion, it forms a 

 protiodide, or a periodide. 



