ANIMAL. 



127 



The fifth tissue which prevails among ani- 

 mals is ihejibrous. This is or may be divided 

 into the tendinous and ligamentous. These are 

 alike subservient to the muscular tissue and to 

 the function of voluntary motion. They con- 

 sist of fibrous, parallel bundles, of a white 

 colour and pearly lustre, of great strength, and 

 possessing little elasticity. 



The sixth tissue which is peculiar to animals 

 (the first of those less universally distributed) is 

 the osseous. This forms the frame-work or 

 skeleton which gives form and fixity to all the 

 other parts entering into the constitution of the 

 higher animals. The essential organic element 

 of bone is a cellular net-work consisting of 

 gelatine, within the meshes of which certain 

 calcareous salts, the phosphate and a little 

 carbonate of lime especially, are deposited in 

 order to give them greater solidity. 



The cartilaginous is generally reckoned as 

 the seventh among the elementary tissues of 

 animals ; it may and has been very properly 

 assimilated to the osseous : the bones are car- 

 tilaginous at first, and with the progress of 

 years many of the cartilages show a tendency 

 to, or do actually become, converted into bone. 

 The cartilages that cover the articular heads of 

 the bones are almost the only ones that show no 

 disposition to undergo this change. The organic 

 element of cartilage is gelatine. 



Thejibro-cartilaginous is a mere modification, 

 although an interesting one, of the cartilaginous 

 or rather of the fibrous tissue. The fibro-car- 

 tilages are very strong, and particularly elastic. 



The horny and calcareous coverings of in- 

 sects, and the Crustacea have uses corresponding 

 to those of the bones. The calcareous shells 

 of the mollusca, too, bear a certain, though 

 a very remote analogy to the skeletons of the 

 higher animals. 



The horny or eighth tissue peculiar to ani- 

 mals might with propriety be reckoned among 

 the number of those that are very widely dis- 

 tributed. We meet with it in the epidermis of 

 man, and as low in the scale at least as the 

 molluscs and annelides ; it is the most universal 

 clothing provided by nature for the bodies of 

 animals. 



So much for the simple tissues entering into 

 the composition of animals, to many of which 

 nothing analogous can be discovered among 

 vegetables. But these are by no means the 

 only solid elements that make up the aggregate 

 of animal bodies. The organs, as we entitle 

 them, for the performance of certain functions 

 so generally encountered among animals, the 

 lungs, liver, stomach, kidneys, testes, ovaries, 

 &c., &c., are so many peculiar compounds of 

 the more simple tissues, occasionally with ad- 

 ditions denominated parenchyma, nothing cor- 

 responding to which has ever been discovered 

 among vegetables. These various organs are 

 associated in animals into groups, denominated 

 systems, which severally tend to the accom- 

 plishment of the individual functions mani- 

 fested by the creature examined, the teeth, 

 tongue, salivary glands, resophagus, stomach, 

 liver, pancreas, and intestinal canal, constitute 

 one great and important system, subservient to 



the conversion of food into nourishment, and 

 the preservation of the individual; the testes, 

 penis, vagina, uterus, and ovaries, in the two 

 sexes, compose another great system by which 

 the species is continued, and so on. 



Besides these solids we have a great variety 

 of fluids, which in animal bodies subserve 

 various and important purposes : we have, for 

 instance, the general nutrient fluid distributed 

 to all parts of their bodies, denominated blood. 

 We have a variety of fluids prepared for aiding 

 or accomplishing the act of digestion, the 

 saliva, gastric juice, pancreatic juice, and bile ; 

 we have various fluids as emunctories of the 

 worn-out parts and particles of the system, 

 the perspiration and the urine ; and we have a 

 peculiar fluid prepared as a means of con- 

 tinuing the species the spermatic fluid. Fluids 

 corresponding in their destination to one or 

 two of these are also met with among vege- 

 tables, but there they are greatly modified. 



Comparison of the vital manifestations, or ac- 

 tions of vegetables and animals. In considering 

 generally the manifestations of vitality in vegeta- 

 bles and animals, we immediately become aware 

 of very distinct and peculiar tendencies in each 

 class. A disposition to produce diversity of parts, 

 and a symmetrical arrangement of these, are as 

 striking features in the acts by which animals 

 are evolved, as the opposite or a disposition to 

 reproduce to infinity similar parts without sym- 

 metry is a character inherent in vegetables. The 

 liver, spleen, heart, intestinal canal, pancreas, and 

 vertebral column, are the principal asymmetrical 

 parts in animals ; the organs of the senses, the 

 lungs, kidneys, testes, ovaries, lateral bones of 

 the head, and extremities, and the muscles, are 

 the principal symmetrical parts ; and these seve- 

 rally cannot be said to be repeated, they only 

 exist in pairs, on either side of the mesial plane. 

 Such accessory and unessential organs as hair, 

 scales, feathers, &c. are the only ones that 

 are found repeated among animals. The very 

 opposite of this tendency prevails among vege- 

 tables; we find nothing like symmetrical ar- 

 rangement on either side of a middle plane, and 

 we see the same parts repeated again and again 

 to infinity, so that any single part, a branch, for 

 instance, becomes an epitome of the entire 

 tree. 



Another peculiarity in the mode in which 

 the vital processes build up vegetables and 

 animals consists in the situation and disposition 

 assigned to the various organs entering into 

 their composition. Whilst in plants the whole 

 of the organs destined to the manifestation of 

 particular functions, the leaves, flowers, sta- 

 mina, pistilla, roots, &c., are placed externally, 

 and their interior or trunk is a mere prop upon 

 which these parts are hung, in animals the 

 whole of the essential organs destined for the 

 preservation of the individual and continuation 

 of the species are concealed, so that their ex- 

 terior is the shell, their interior the receptacle 

 for the especial lodgement and protection of 

 these. 



Such diversity in the arrangement of the 

 parts composing vegetables and animals does 

 away with the necessity for the existence among 



