122 



ANIMAL. 



stead of obeying the universal law of gravita- 

 tion, vegetables, for instance, shoot upwards, 

 and propel their juices from the roots to the 

 leaves; animals also distribute their blood in 

 opposition to the laws of gravitation, and by 

 their powers of motion overcome the universal 

 physical law that tends to fix them in one place. 

 The force of cohesion is not a merely passive 

 property in the organized as it is in the unorgan- 

 ized world, and the laws of chemical affinity 

 are especially set at nought both by plants and 

 animals, their constituent elements being even 

 generally united into combinations the con- 

 trary of those which these laws ordain. Animals 

 and vegetables are farther abstracted from the 

 general law of caloric, the more perfect of them 

 at least having a specific temperature, inde- 

 pendent of that of the medium which sur- 

 rounds them, and which varies in conformity 

 with chances in the peculiar actions of which 

 in them it is the product. 



There is even a distinction between the 

 organized and unorganized world to this extent, 

 that while the physico-chemical laws do- 

 minate the inorganic world rigorously, and the 

 bodies that belong to it seem to have begun 

 to be as they continue to exist through, or in 

 harmony with, their prescriptions, no organized 

 body known has either sprung into being or 

 continues to exist through the agency of purely 

 physical or purely chemical forces. The whole 

 of the special properties of organized beings 

 consequently must be held to be effects of the 

 agent denominated life, and of the laws which 

 this agent originates. The organized world is, 

 therefore, a creation within a creation, a some- 

 thing superadded to the material universe and 

 to the generally pervading forces that keep its 

 parts in their places, and endow them with 

 what may be called their necessary pro- 

 perties. 



Nor is it only whilst endowed with life that 

 organized differ from unorganized beings. 

 Many of the distinguishing and peculiar pro- 

 perties of these remain for a season at least 

 after life has left the organization it had built 

 up. The extensibility and elasticity of the 

 tissues of animals especially, were held by 

 the distinguished Bichat as even independent 

 of life, \\hich he owned increased their energy, 

 but which he denied as their cause, seeing that 

 they continue to exist after death. These pro- 

 perties are undoubtedly peculiar, and are at 

 all events effects of forces which life has called 

 into play, both the tissues which possess 

 elasticity and contractility, and these qualities 

 themselves having been engendered under the 

 influence of vitality. 



In these properties, forces or capacities of 

 action common to all the objects of nature, 

 unorganized as well as organized, we see the 

 objection to the old denomination of inert, 

 which was applied to one of the great classes. 

 Nothing that exists is inert or inactive ; but 

 organized have an infinitely wider field of 

 action than unorganized bodies. Let us, in 

 illustration of this position, examine in succes- 

 sion the various actions by which bodies gene- 



rally originate, continue their existence, un- 

 dergo such modifications as they present in the 

 course of their existence, and by which they 

 came to an end or die. 



Origin. Unorganized bodies, minerals for 

 example, commence their existence from the 

 instant that circumstances exterior to them- 

 selves detach them from the mass of some 

 other mineral, precipitate them from a state of 

 solution in a fluid, or bring their constituent 

 elements into a position in which they can 

 combine together. In this, it is evident, there 

 is nothing like generation, as the term is 

 applied to organized bodies, which all alike, 

 vegetables as well as animals, spring from a 

 molecule, an atom, which has once belonged 

 to, and which has proceeded from, a being 

 similar to themselves. Vegetables spring from 

 seeds, animals from eggs. Organized beings, 

 therefore, are engendered, their existence 

 is a consequence of that of other beings like 

 themselves ; and in their succession they 

 depend one upon another. Minerals, on the 

 contrary, have no powers of reproduction ; 

 they cease to be, if at any time they originate 

 another mineral, and they are individually in a 

 state of perfect independence.* 



In the mode in which organic and inorganic 

 bodies continue their existence, there is also a 

 striking dissimilarity. In the inorganic world 

 we observe no actions tending to preserve the 

 individual, other than those which have pre- 

 sided over its formation : it continues to exist 

 through the continuing agency of the affinities 

 and of the attraction of cohesion which called 

 it into being. Animals and vegetables, on the 

 contrary, have special powers for their pre- 

 servation superadded to those by the peculiar 



* It were long to enter here into the discussion 

 of what has been called equivocal generation, which, 

 if admitted, militates against several of the in- 

 ferences just deduced. It is quite certain that 

 infusions of any organized substance do speedily 

 become filled with animals distinct in their kinds 

 and lately shown to be much more complicated in 

 their structure than was long supposed. It is 

 almost as difficult to conceive that these infusory 

 animals proceed from eggs contained in the fluids 

 in which they appear, as to imagine that they 

 proceed from the combination, per se, of their con- 

 stituent elements. Did we incline to admit the 

 reality of equivocal generation, it is certain that 

 its occurrence must be referred to other than the 

 general laws of nature, with which we have al- 

 ready had occasion to show the laws of life to be 

 in opposition, much rather than in harmony. It 

 would be absurd to believe that these general 

 physico-chemical laws, absolutely inimical to life, 

 should at any time call it into being. Equivocal 

 generation being acknowledged, therefore, it would 

 seem necessary to infer a third order of laws be- 

 sides the physico-chemical and the vital, the 

 nature of which is altogether unknown to us. 

 The number of creatures which were presumed 

 to owe their being to equivocal generation, has 

 been very much curtailed by the progress of science 

 in modern times ; and it is not impossible that the 

 mystery which still overhangs the genesis of the 

 infusoria may one day be dissipated, and their pro- 

 duction demonstrated to be in harmony with those 

 laws which are known to preside over the origin 

 of higher classes of vegetables and animals. 



