ANIMAL. 



141 



and more numerous, and the nervous system 

 generally more and more complicated as we 

 rise in the scale of animal creation. The ner- 

 vous system is before long found to consist of 

 other parts than a series of similar ganglions 

 supplying at once the organs of sensation and 

 those of digestion ; it has a central part super- 

 added, from which issue immediately the 

 nerves that supply the organs of the senses, 

 sight, hearing, taste, and smell, which at the 

 same time make their appearance with their 

 especial capacities. TJiis central superadded 

 portion is the brain, with its prolongation in 

 the vertebrata entitled spinal marrow. Nor in 

 the more perfect classes of the animal king- 

 dom is the nervous system even thus simple ; 

 among them it consists essentially of two 

 grand divisions, the one including the brain 

 and spinal cord and the nerves thence pro- 

 ceeding, the other constituted by the system of 

 the great sympathetic, or that series of ganglions 

 which, situated on either side of the vertebral 

 column, from the head to the pelvis, are con- 

 nected with one another, and with the cerebro- 

 spinal system, by branches of communication, 

 and furnish the digestive apparatus with almost 

 the whole of the numerous nerves it receives. 



The nervous system in its relative degree of 

 development and complexity becomes the 

 ultimate standard by which the perfection of 

 animals is estimated, and their place in the 

 scale of creation assigned to them : if man 

 stand alone and unattended, as he undoubtedly 

 does, upon the summit of the pyramid, it is 

 only because he possesses in his brain the 

 organs of certain moral and intellectual facul- 

 ties which occur in no other living thing; these 

 confer on him his humanity; these are the ma- 

 terial parts to which the soul is wedded during 

 his existence. 



In intimate connection with the functions of 

 phrenic or animal life, and developed nearly 

 in the same ratio, is the muscular system, the 

 most universal agent of locomotion. Exceed- 

 ingly simple at first, and operating at great 

 disadvantage through a want of levers and 

 points of support, we trace it becoming gra- 

 dually more complicated as we ascend, and, 

 finally, provided with a complementary skeleton 

 or frame-work by means of which it acts to the 

 best advantage. The skeleton among animals 

 is of two kinds, external and horny, internal 

 and osseous. In the first case the muscular 

 system is inclosed within the resisting pieces 

 which it has to move; in the second it is 

 without these, and is arranged around them. 

 The bones and muscles together compose the 

 numerous and variously fashioned instruments 

 with which animals accomplish the promptings 

 of their inward appetites and instincts. They 

 form feet, fins, hands, the prehensile tail, &c. 

 The muscular system, and a modification of 

 the osseous, the cartilaginous, moreover, com- 

 pose the most universal instrument by which 

 animals communicate their vicinity, their states, 

 their dispositions or affections, &c. to one ano- 

 ther this is the larynx. 



The means by which species are continued, 

 are extremely varied. The very lowest tribes 



of animals we have seen shooting forth buds 

 exactly like vegetables, and these being in due 

 season detached from the body of the parent, 

 find themselves fitted to commence an inde- 

 pendent existence. At the next step we take 

 in ascent, however, we meet with particular 

 organs of reproduction ; and, singular enough, 

 the moment these exist they are not of one, 

 but of two kinds, denominated male and fe- 

 male. Sometimes these organs are possessed 

 by single individuals, far more commonly, 

 however, they are divided between two, whence 

 the so uniform division of the beings com- 

 posing the animal kingdom into sexes. The 

 simplest form of the male organ of generation 

 is a gland secreting a fecundating fluid (the 

 testis) and an excretory duct: the simplest 

 form of the female apparatus of generation is 

 a gland or body producing germs (the ovary) 

 and an excretory duct. In a greater state of 

 complication or development these essential 

 parts in the male have an instrument super- 

 added to them by which the fecundating fluid 

 is carried directly into the body of the female, 

 and in the female the ovary has a dilatable 

 cavity superadded in which the germ remains 

 for a season, and until its included embryo 

 attains such a state of development as is com- 

 patible with its more independent existence 

 surrounded by the circumstances amid which 

 it is afterwards to live. In the higher classes, 

 the connection between the parent and offspring 

 does not cease immediately on the birth of 

 the latter, and in the highest of all we find 

 the female furnished with a complementary 

 apparatus (the mammae), from which she fur- 

 nishes her young with food during the first 

 period of its existence. 



Actions of animals. The foregoing rapid 

 sketch of the grand features of distinction 

 among animals with reference to their struc- 

 ture naturally leads to the inference of di- 

 versity of function in harmony with the pecu- 

 liar organization possessed by each. In the 

 lowest grades of animal existence we have 

 seen to how simple a process the act of nutrition 

 this act so complicated among the more 

 elevated tribes, is reduced. It consists merely 

 of imbibition or absorption by and of exha- 

 lation from the general surface of the body. 

 The matters absorbed appear to be assimilated 

 incontinently, or to be made a part of, and to 

 receive the form proper to, the animal in the 

 instant of their assumption : applied imme- 

 diately to the homogeneous organism, the 

 nutriment is forthwith made a portion of its 

 substance. The vital decomposition of the 

 bodies of these lower animals is accomplished 

 with the same simplicity and directness : the 

 surface that absorbs is also that which exhales 

 the worn-out particles of the system. 



The first step by which nutrition becomes 

 more complex, as we rise in the scale of cre- 

 ation, is the institution of a process of solution 

 (digestion), by which the matters appropriated 

 as aliment are prepared for reception into 

 the body. This process of solution is accom- 

 plished by powers inherent in the animal itself, 

 within a cavity destined for the purpose. In 



