384 VITALITY. 



a single generation. That acorn was itself borne on an oak, which sprang from 

 an acorn ; which must have held the type of the types in the second acorn, and 

 of every leaf of the tree which the second acorn produced. In fact, if we con- 

 ceive the oaks of the world to have sprung from a single acorn, on the hypothesis 

 of those who deny the specialty of the vital principle, that acorn must have 

 had in itself the types of all the oaks that have ever been produced; for agencies 

 like those of electricity, heat, &c., can only work upon what they find; and if 

 there should be a bud on the last oak that had not its representative in the first 

 acorn, that bud would be a result without a corresponding antecedent. 



Let us remark that the difficulty we here encounter arises from the peculiar 

 manner in which life is transmitted from living things to their successors. No 

 difficulties of this kind meet us in the history of the drop of water, though we 

 saw that it had a history reaching back to the very limits of time. Its parti- 

 cles may have been many times round the world ; some of its parts may have 

 been ice, or steam, or free oxygen and hydrogen. The changes they may have 

 passed through quite exceed our calculation, but they were either chemical or 

 mechanical; and though the series is long, the terms are simple — there is no 

 accumulation of difficulty. In the case of crystals the nucleus is the requisite 

 initium, or rather the molecules of the mineral substance have characters suffi- 

 cient to determine the form of the crystal. But the crystal is homogeneous, and 

 has no special organs such as are possessed by plants and animals. The pro- 

 duction of such an organ as the eye from the mere development of physical 

 peculiarities pertaining to the germinal vesicle and spot can hardly be conceived 

 to be possible. 



In fact, the notion that every seed contained the perfect plant in miniature 

 belonged to a former age, and has long been regarded as exploded; yet it seems 

 to me to be an inevitable conclusion if nothing is concerned in the germination 

 and subsequent growth of the seed but such as are of the nature of light, heat, 

 electricity, &c. It is, however, certain that the seed possesses vitality; and 

 without attempting to define what the vital principle may be, it appears reason- 

 able to assign to it a certain special directive agency, by virtue of which it is 

 enabled to apply the ever-present forces of heat, actinism, &c., in the construction 

 of a plant of its own proper species. But it is manifest that a vitality thus endued 

 cannot be correlative with any of the known imponderable forces. 



Another point worthy of attention is the stability of form and structure ob- 

 servable through many generations of the same species. Whatever may be the 

 wondrous exactness of the embryo prototype, the accidental influences of heat, 

 moisture, light, &c., in the course of growth are so great that it is hardly possible 

 to conceive that, with only the physical character of the embryo (itself produced 

 under these varymg agencies) to determine the succeeding form, similarity 

 should be preserved through so many ages and in so many collateral lines of 

 descent 



The termination of life, on the supposition that the vital principle is analogous 

 to known forces, ought to yield indications of some kind or other. Death is a 

 common event, and one that lies completely open to observations of all kinds. 

 In the animal world it is in our power to produce death under almost any con- 

 ditions we may choose as most favorable for investigation; and it. is an event so 

 interesting that the discovery of its nature would be considered the greatest 

 achievement of the intellect of man; yet the nature of death is absolutely un- 

 known. The most delicate tests for indicating minute changes in electrical, 

 thermal, and other conditions have been applied at the moment of death, and 

 have shown no sign. Now it is certain of the forces of heat, light, motion, 

 &c , that they are absolutely indestructible; they may be converted one into 

 another, but they cannot cease to exist. If the vital principle was analogous to 

 these agencies it might escape in any one of them; but of this no well-ascer- 

 tained trace has been observed in any investigation of the phenomena of death. 



