INS 



INS 



veyances of lands, and registering them, 

 in order to secure men's titles ; but this 

 has been objected to by the landed inte- 

 rest in parliament, chiefly from motives 

 of delicacy. 



INSCRIBED, in geometry. A figure 

 is said to be inscribed in another, when 

 all its angles touch the sides or planes of 

 the other figure. 



INSCRIPTION, a title or writing carv- 

 ed, engraved, or affixed to any tiling, to 

 give a more distinct knowledge of it, or 

 to transmit some important truth to pos- 

 terity. The inscriptions mentioned by 

 Herodotus and Diodorus Siculus suffi- 

 ciently shew that this was the first me- 

 thod of conveying instruction to mankind, 

 and transmitting the knowledge of history 

 and sciences to posterity ; thus the an- 

 cients engraved upon pillars both the prin- 

 ciples of sciences, and the history of the 

 world. PisistraUis carved precepts of 

 husbandry on pillars of stone ; and the 

 treaties of confederacy between the Ro- 

 mans and Jews were engraved on plates 

 of brass. Hence, antiquarians have been 

 very curious in examining the inscriptions 

 on ancient ruins, coins, medals, &c. 



INSECTS, in natural history. We 

 have, under the article ENTOMOLOGY, 

 given an account of the Linnaean system 

 of this department of natural history. 

 We shall, in this place, enumerate some 

 of those circumstances which form the 

 line of distinction between insects and 

 other animals. Insects are not furnish- 

 ed with red blood, but instead of it their 

 vessels contain a transparent lymph. This 

 may serve to distinguish them from the 

 superior animals, but it is common to 

 them with many of the inferior ; though 

 Cuvierhas lately demonstrated the exist- 

 ence of a kind of red blood in some of 

 the vermes. They are destitute of inter- 

 nal bones ; but, in place of them, are fur- 

 nished with a hard external covering, to 

 which the muscles are attached, which 

 serves them both for skin and bones ; 

 they are likewise without a spine formed 

 of vertebrae, which is found in all the su- 

 perior classes of animals. They are fur- 

 nished with articulated legs, six or more ; 

 this circumstance distinguishes them from 

 all other animals destitute of a spine 

 formed of vertebrae. A very great number 

 of insects undergo a metamorphosis : this 

 takes place in all the winged insects. 

 They frequently change their skin in the 

 progress of their growth. A very great 

 number of insects are furnished with jaws 

 placed transversely. 



The wings with which a very great 

 VOL. VI. 



number of insects are furnished distin- 

 guish them from all other animals, which 

 are not furnished with a spine compos- 

 ed of vertebrae. Insects are generally 

 oviparous; scorpions and aphides, dur- 

 ing the summer months, are viviparous. 

 Insects have no nostrils, are destitute 

 of voice : they are not furnished with a 

 distinct heart, composed of ventricle and 

 auricle. Incubation is not necessary for 

 hatching their eggs. Insects, like -all 

 other organized bodies, which form the 

 animal and vegetable kingdoms, are com- 

 posed of fluids and solids. In the four 

 superior classes of animals, viz. quadru- 

 peds, birds, reptiles and fishes, the bones 

 form the most solid part, and occupy the 

 interior part both of the trunk and limbs ; 

 they are surrounded with muscles, liga- 

 ments, cellular membrane, and skin. 

 The matter is reversed in the class of 

 insects ; the exterior part is most solid, 

 serving at the same time both for skin 

 and bones ; it encloses the muscles and 

 internal organs, gives firmness to the 

 whole body, and, by means of its articu- 

 lations, the limbs, and different parts of 

 the body, perform their various motions. 

 In many insects, such as the crab, lob- 

 ster, &c., the external covering is very 

 hard, and destitute of organization ; it is 

 composed of a calcareous earth, mixed 

 with a small quantity of gelatine, formed 

 by an exudation from the surface* of the 

 body. As its great hardness would check 

 the growth of the animal, nature has pro- 

 vided a remedy ; all of these crustaceous 

 insects cast their shell annually. See 

 CRUSTS. The skin of most of the other 

 insects is softer and organized, being 

 formed of a number of thin membranes, 

 adhering closely to one another, and put- 

 ting on the appearance of hern. It owes 

 its greater softness to a larger proportion 

 of gelatine. The muscles of insects con- 

 sist of fibres formed of fasciculi ; there 

 are commonly but two muscles to pro- 

 duce motion in any of their limbs, the one 

 an extensor, the other a flexor. These 

 muscles are commonly attached to a ten- 

 don, composed of a horny substance, con- 

 nected to the part which they are des- 

 tined to put in motion. In most insects, 

 the brain is situated a little above the 

 oesophagus; it divides into two large 

 branches, which surround the oesopha- 

 gus, and unite again under it, from which 

 junction a whitish nervous cord pro- 

 ceeds, corresponding to the spinal mar- 

 row of the superior animals, which ex- 

 tends the whole length of the body, 

 forming in its course twelve or thirteen 

 Oo 



