ANIMAL. 



139 



and fluids they surround and include. This 

 tonicity or peculiar contractility disappears 

 in great part with the cessation of life : a 

 wound made in a dead body never gapes as 

 it does in a living one. Something of the 

 same kind exists in vegetables ; the sap as- 

 cends with greatly increased velocity in the 

 young shoots under the influence of stimuli of 

 different kinds, and its flow is checked by nar- 

 cotics and altogether arrested by poisons ; it is 

 probable, therefore, that it takes place in con- 

 sequence of a vital tonicity or contractility in 

 the sides of the sap-vessels which contain it. 



From this general review of the physical 

 construction and vital phenomena of the two 

 grand classes of organized beings, vegetables 

 and animals, it is impossible not to remark the 

 strong features of resemblar.ee, and yet the 

 numerous points of difference they exhibit. 

 Both have a beginning, which happens very 

 much in the same way in each ; bolh live as 

 individuals by the susception of aliment and 

 its prepration by a variety of processes, which, 

 in their essence, differ but little from one an- 

 other ; both continue themselves as kinds in a 

 surprisingly similar manner ; both exhibit the 

 changes denominated age; both have a merely 

 temporary existence, consequently both exhibit 

 the phenomenon entitled death, and both are 

 decompounded after the cessation of life, their 

 constituent elements assuming new shapes, in 

 obedience to the general laws of chemical 

 affinity, which had been set at nought during 

 the existence of the individuals in either class. 

 Notwithstanding these striking points of re- 

 semblance between vegetables and animals in 

 all that is essential or general, it is impossible, 

 as we have seen, to condescend upon par- 

 ticulars without immediately detecting differ- 

 ences that distinguish in the most marked 

 manner the individuals of the one class from 

 tliose of the other. It is always in their lowest 

 or most simple species that we remark the 

 most striking similarity between vegetables 

 and animals, and it is among these that we 

 constantly find ourselves most at a loss for 

 characters distinctive of each. We observe no 

 evidence of anything like a connected chain 

 of being from the lowest or most simple, to 

 the highest or most complicated vegetable, and 

 from this through the most inferior animal 

 upwards to man ; it is, on the contrary, in the 

 extremes or lowest grades of each that the 

 greatest similarity prevails; here vegetables 

 and animals approximate very closely, here 

 they literally inosculate, but from this common 

 point they begin to form two distinct series, 

 which diverge ever more and more widely 

 from one another as they ascend. Without 

 attention to particulars, it would seem impos- 

 sible to adduce as ultimate terms of distinction 

 between vegetables and animals, other faculties 

 than those of voluntary motion and sensation 

 as peculiar to the latter, in virtue of the one of 

 which powers they are rendered in a great mea- 

 sure masters of their own existence, whilst by the 

 other they are endowed with consciousness of 

 many of the various acts that take place 



within, and of the phenomena that occur 

 without them. Even this distinction, how- 

 ever, is only applicable as regards species con- 

 siderably raised above the lowest; would we 

 indicate the differences between the most in- 

 ferior members of either series we must con 

 descend upon particulars, and, in some in- 

 stances, even call in analogy and inference to 

 our aid in laying down the chart of their re- 

 semblances and dissimilarities. 



COMPARISON OF ANIMALS WITH ONE ANOTHER. 



This head is also comprised within that of 

 our entiie Cyclopaedia. The glance we shall 

 cast over the field it embraces will, therefore, 

 be very cursory, and the views taken of the 

 objects it presents extremely general. 



Physical qualities and material constitution 

 of animals In point of size, animals differ 

 most widely from one another. The existence 

 of some is only made known by the aid of a 

 powerful microscope, the length of others ex- 

 ceeds a hundred feet, and their weight amounts 

 to many tons. These extremes include animals 

 of every intermediate bulk. 



Theyb/vrt assumed by animals presents many 

 more interesting particulars for study and in- 

 vestigation than the mere bulk of their bodies. 

 The consideration of this accident has even 

 been made the ground of a classification of the 

 objects included within the animal kingdom 

 by several naturalists, and although not adopted 

 as the sole basis of any one now generally 

 received, it nevertheless furnishes the element 

 upon which several of the classes even of the 

 most recent aie established. Some animals 

 present themselves in the likeness of a globule, 

 others of a Jilument, and others of a small 

 flattened membrane (the cyclides). Various 

 animals, again, from exhibiting no uniform or 

 regular shape, have been entitled amorphous or 

 heteramorphous. 



Animals which exhibit a determinate form 

 naturally arrange themselves into two classes ; 

 their bodies are either disposed around a 

 centre, or they consist of two similar halves 

 cohering along a middle plane or axis; the 

 first are the radiata, the second the binaria 

 or symmetrica of naturalists. The radiata are 

 not a very extensive class of animals, neither is 

 their organization extremely complicated. The 

 symmetrical is a much more numerous class 

 than the radiated, and includes within its limits 

 creatures of such simple structure as the en- 

 tozoa, and of such complicated fabric as quad- 

 rupeds and man. Of the symmetrical animals, 

 some consist of a mere trunk without appen- 

 dices or limbs ; those that are provided with 

 limbs, again, have them in the shape of feet, 

 fins, wings, or hands, according to the media 

 in which they live. In some the body forms 

 as it were a single piece, in others it is divided 

 into portions, such as head, trunk, and tail. 

 Sometimes it is naked ; at others it is covered 

 with shells, scales, spines, hair, &c. Some- 

 times the general integument is continuous, 

 unpierced by any opening that leads to the 

 interior, at others it is reflected inwards, and 

 lines extensive cavities there contained. 



