144 



ANIMAL. 



ral systemic circulation, now with the pul- 

 monic, being situated in the one case in the 

 course of the aerated, in the other in that of 

 the unaerated current of blood. In the most 

 elevated classes of animals, finally, the double 

 circulation is effected by means of two hearts, 

 one dedicated to the projection of the un- 

 aerated blood into the lungs, the other to the 

 propulsion of the aerated fluid through the 

 general system. These two hearts, indeed, 

 adhere to one another, and are usually spoken 

 of as if they constituted no more than a single 

 organ, having however four cavities, two 

 auricles and two ventricles, but they are 

 not less distinct on that account, and are 

 severally the centre of a particular circula- 

 tory system, one of which commencing in the 

 cavities for the venous or unaerated blood, ex- 

 tends through the respiratory apparatus (then 

 uniformly a lung), and back to the cavities for 

 the arterial aerated blood ; the other, com- 

 mencing in the cavities just named, extends to 

 every part of the organization, and terminates 

 in the cavities for the unaerated blood, where 

 the lesser round recommences, to be followed 

 in its turn by the greater, and so on, during 

 the whole period of existence. 



Assimilation appears to be identical in all 

 animals ; it is the ultimate term of nutrition, 

 and however varied the apparatus that minis- 

 ters to the act, the act itself we may presume 

 not to differ in its essence in one animal from 

 what it is in another. 



Akin to assimilation we have secretion, and 

 this is a function that offers extensive differences 

 in every class of the animal kingdom. It is 

 generally spoken of as of two kinds, excretion, 

 and secretion, properly so called. In the lowest 

 tribes excretion is quite simple, consisting of a 

 mere exhalation from the general surface of the 

 body. In the more elevated we find another 

 and very important form of excretion super- 

 added, that, namely, of the urine, the nature of 

 which, and the mode in which it takes place, 

 we have already indicated in speaking of the 

 structure. Secretion, however, even in the 

 classes but a little raised above the lowest, is a 

 function of much more varied import, and con- 

 sists of a great many other processes than that 

 by which the bodies of animals are depurated 

 and their blood maintained in a state fit to 

 supply all the wants of the system. We ad- 

 vance but a little way before we begin to detect 

 distinct organs destined for the secretion of 

 peculiar fluids from the general mass of cir- 

 culating nutriment, evidently subservient in 

 many cases to the most important ends of the 

 economy, and by no means destined to be 

 rejected from the system as useless, like the 

 excretions properly so called. It seems even 

 that it is by a process analogous to secretion 

 that the imponderable matters the heat, light, 

 and electricity, which we have acknowledged 

 as elements in the constitution of organized 

 beings, are eliminated. 



All animals possess sensibility or sensation, 

 though evidently in the most dissimilar degrees. 

 Some have been supposed to possess the faculty 

 of perceiving impressions made upon them by 



external objects, but to have no power of re- 

 acting upon external nature, they being without 

 the faculties which in the higher classes prompt 

 to action. This state, however, of animal ex- 

 istence is rather hypothetical than demonstrable, 

 and in animals generally we observe not only the 

 aptitude to be impressed, but inherent capacities 

 inducing reaction upon the world around them. 

 The sensitive life of these beings consequently 

 consists of two items the senses and their 

 organs, external and internal, by which im- 

 pressions are received and cognized, and the 

 affective and intellectual faculties by which the 

 motives to action, the propensities, sentiments, 

 instincts, appetites, &c., are originated, and 

 the means and modes of accomplishing their 

 promptings are supplied. 



Animals evidently differ immensely in the 

 degrees in which they are endowed with ex- 

 ternal and internal senses. Some appear to 

 possess none of the external senses save touch ; 

 others, in addition to this, have taste and smell ; 

 the most perfect besides these three reckon 

 sight and hearing. The internal senses, in like 

 manner, are more or less acute, more or less 

 numerous, according to the consitution of ani- 

 mals : those of hunger and thirst are probably 

 universally distributed, and the most keenly 

 felt ; then come those which induce the respira- 

 tory act, the sexual act, &c. ; and here we 

 find ourselves among the propensities which 

 exist in very different numbers and kinds in 

 every different species of animal. Some tribes 

 tend their offspring, others leave their progeny 

 to the care of accident, which in this case 

 always suffices for their protection ; some con- 

 gregate in herds or shoals, others live solitary 

 or in pairs; some are bold and rapacious, 

 others timid and gentle, &c. When we ex- 

 amine animals generally, with reference to the 

 sentiments or moral faculties, we find them 

 still more or less like each other in many 

 respects, some being cautious or cowardly, 

 proud or haughty, persevering or obstinate, &c., 

 in various proportions. When we contrast all 

 other animals with man, however, in regard to 

 moral endowment, we immediately perceive 

 the broad, the impassable line of difference that 

 runs between the lord of creation and all the 

 other beings that with him partake of life. The 

 feeling which leads man to view his actions in 

 their bearing upon others or in relation to jus- 

 tice, is extremely weak among animals, if in- 

 deed it do actually exist among them at all. 

 The same may be said of the sentiment which 

 leads mankind to wish well to all, and to 

 succour and relieve those that are suffering and 

 unfortunate. The feeling, again, that raises 

 man to the imagination of a something beyond 

 nature, the sentiment that inclines him to reve- 

 rence and adore his Maker, thus in one way re- 

 vealed to him, and the wonderful impulse that 

 leads him to look beyond time and his merely 

 temporary existence, and thence to conceive in- 

 finity and eternity, are so many moral attributes 

 which man alone, of all created things, possesses. 

 Similar diversities in intellectual endowment 

 are apparent when we survey the animal king- 

 dom at large. Intelligence appears utterly 



