D 



I 232 ] 



D 



or covering of certain larvae ; gene- 

 rally used plurally, mdmice. 

 INDU'SIAL LIMESTONE. A fresh -water 

 limestone to which the name in- 

 dusial has been given, from its 

 containing the indusiae, or cases, 

 of the larvse of Phrygania. 

 IN.EQUILA'TERAL. } Having unequal 

 INEQUILA'TERAL. ) sides ; in con- 

 chology, when the anterior and 

 posterior sides make different 

 angles with the hinge. 

 INE'QTJIVALVE. j Where one valve 

 INEOJJIVA'LVULAR. j is more convex 

 than the other, or dissimilar in any 

 respect, as in the common oyster. 

 INFLORESCENCE, (inflorescentia, Lat.) 

 A word used to express the par- 

 ticular manner in which flowers 

 are placed upon a plant ; this by 

 older writers was denominated the 

 modus florendi, or manner of 

 flowering. Botanists distinguish 

 many kinds of inflorescence, under 

 the name swhorl, cluster or raceme, 

 spike, corymb, fascicle, tuft, umbel, 

 cyme, panicle, bunch, &c. 

 INFUNDIBTJ'LIFORH. (from infundibu- 

 lum and forma, Lat.) Funnel- 

 shaped : in botany, applied to a 

 monopetalous corolla, having a 

 conical border placed upon a tube. 

 INFUSO'RIA. } Beings so 



IMFT/SORY ANIMA'LTJLES. j extreme- 

 ly minute as to be invisible to the 

 naked eye, and which have only 

 been discovered since the invention 

 of the microscope. The infusoria 

 have been divided into two orders, 

 the Rotifera and Homogenea. The 

 order Rotifera comprises many 

 genera, Brachionus, Furcularia, 

 Tubicolaria, and Yaginicola : the 

 Homogenea comprises TJreolaria, 

 Trichoda, Leucophra, Kerona, Hi- 

 mantopes, &c., &c. The most 

 extraordinary genus of all is the 

 Proteus. It is not possible to 

 assign to them any determinate 

 form ; their figure changes momen- 

 tarily ; sometimes rounded, some- 

 times divided. The bodies of the 



infusoria, are, for the most part, 

 gelatinous. 



When we place a drop of any 

 infusion of animal or vegetable 

 matter under a powerful micro- 

 scope, and throw a light through 

 that drop, and through the micro- 

 scope to the eye, we discover in 

 the drop of water various forms of 

 living beings, some of a rounded, 

 some of a lengthened form, and 

 some exhibiting ramifications shoot- 

 ing in all directions, but all ap- 

 parently of a soft, transparent, 

 gelatinous, and almost homogeneous 

 texture. These beings constitute 

 the lowest form of animals with 

 which we are at present acquainted, 

 and they were at first considered asto- 

 matous, that is, without any mouth, 

 and agastric, or possessing no 

 stomach, and were called infusoria, 

 a denomination explanatory merely 

 of their habitat, but not of their 

 structure. Upon further exami- 

 nation, it was discovered that there 

 existed animalcule of a higher 

 denomination ; these exist in every 

 stagnant pool of water, in every 

 river, and in the ocean. Upon 

 examining with great care many 

 years since the effects of coloured 

 infusions upon these minute ani- 

 malculae, it was found that they 

 devoured great quantities of the 

 coloured matter in which they 

 were placed, and that they convey- 

 ed it into internal cavities or 

 stomachs, which are sometimes 

 extremely numerous in them. 

 Those cavities exist in almost every 

 known genus. Sometimes there 

 are nearly 200 stomachs in a single 

 animalcule. Animalcules are found 

 so exceedingly minute that nearly 

 five hundred millions are contained 

 in a single drop of water, that is, 

 as many as there are individuals of 

 our own race on the face of the 

 earth. In those minute beings 

 which constitute the simplest forms 

 of animals, there are numerous 



