Volume 1

The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd.

Date:
1836-59
Catalogue details

Licence: Public Domain Mark

Credit: The cyclopaedia of anatomy and physiology / Edited by Robert B. Todd. Source: Wellcome Collection.

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    be confined to a few weeks, months, or years, or be extended to centuries, we cannot tell. Nor is it only whilst endowed with all their peculiar and inherent properties that organized differ from unorganized bodies. No longer manifesting their especial powers, organized bodies begin to be disintegrated ; their con- stituent elements, held together in opposition to the laws of chemical affinity, become ame- nable to these, and forthwith enter into new combinations, which imply the utter destruc- tion of the organization as it had been formed, and hitherto preserved. Organized beings, as they alone die, so do they also alone undergo putrefaction—a process nothing precisely si- milar to which occurs in the inorganic world. From this review of the distinguishing pecu- liarities of organized and unorganized bodies, it appears that organization implies vitality, and that organization and life are insepara- ble conditions. It would be going too far to say that they were synonymous terms: I organization is the mode of structure proper to living beings; life is the series of actions they exhibit. And this in fact appears to be about the least objectionable definition of life than can be given : life is the series of actions manifested hy organized beings; would we go farther, we must condescend upon an enumera- tion of these actions,—namely, incipience by a genesis or creation; temporary endurance as individual by nutrition, and indefinite continu- ance as species by reproduction, modification during the term of existence known by the title of age, and end by death, to which spe- cific acts or phenomena must be added the peculiar inherent power which living beings possess of overcoming the general physico- chemical laws that dominate the rest of the universe. Thus far we have discussed and contrasted the physical qualities and phenomena common to organized or living beings at large, with such as inhere or are manifested by unorganized bodies generally, more especially minerals; we have still left untouched those that severally pertain to the two grand divisions of the or- ganized world, and that are peculiar to each living thing individually; and here we shall find that the manifestations of vitality are al- most as various as the species that people the earth. In the same manner as we have hitherto gone on contrasting first the material compo- sition, and then the actions of organic and inorganic bodies, we shall still proceed by comparing the material composition and the capacities of action of the different classes of organized beings first, and next of the several individuals composing these classes one with another. Comparison of animals and vegetables. Animals and vegetables were longheld essenti- ally and irreconcilably distinct from one another. We have already had occasion, however, to observe in how many particulars they are iden- tical. The material composition of both is often in opposition with the general physico-chemical laws, both are made up of a combination of solids and fluids, both consist of a variety of heterogeneous parts, and both have determinate sizes which they cannot exceed. Moreover, both are possessed of vitality,—in other words, both commence by a genesis, preserve them- selves as individuals by nutrition, and as spe- cies by reproduction ; both grow by intus-sus- ception, undergo the mutations which are denominated ages, endure for a time, present themselves in health or labouring under disease, and both decay and die. How intimately ani- mals and vegetables are associated, how nearly they resemble one another, will farther appear as we advance in the following Comparison of the general physical qualities and material coinposition of Vegetables and Animals.—As a general axiom the material constitution of vegetables may be said to be less complex than that of animals; this at least is more especially the case as the individuals at the top of the two scales are concerned. No distinguishing feature of either class is derivable from general diversity of Size. Be- tween the microscopic lichen and infusory ani- mal, and the gigantic adansonia and whale, plants and animals of every intermediate mag- nitude are encountered. Neither is there much to be said upon the differences which vegetables and animals pre- sent when their Forms are contrasted. The forms of many are alike amorphous, or simply globular; certain pulverulent fungi in the one class, and monads in the other, resemble each other greatly. Among both, indiHduals also occur whose parts are disposed around a centre; yet we do not advance far before we discover a peculiarity in animals, namely, composition by the union of two similar or symmetrical halves along a middle line or axis, nothing similar to which has even been imagined in tlie vegetable world, the members of which on the contrary often exhibit a horizontal division, but without anything of symmetry, into root and branches. As a general law the animal kingdom may be said to affect the globular or simply produced form, with radii in the shape of extremities sent off from a central part; the vegetable to exhibit a greater tendency to ramification or division into branches. In point of chemical composition animals and vegetables consist very nearly of the same elements: oxygen, hydrogen, carbon, nitrogen, phosphorus, sulphur, iodine, bro- mine, chlorine, potassium, sodium, calcium, silicium, magnesium, manganese, and iron have been detected in both; aluminium and copper have hitherto only been discovered in vegetables, and fluor only in animals. But these elements are united in each in very dif- ferent relative proportions. Carbon predomi- nates greatly in the more solid parts of vege- tables, nitrogen in the bodies of animals gene- rally, although to this rule there are many notable exceptions; albumen, fibrine, and gelatine all contain much more carbon than nitrogen, and certain fungi include a very large proportion of nitrogen in their composition. Several ele- ments, met with abundantly in animals, occur but sparingly distributed among vegetables,