SEEDS AND THEIR GERMINATION. 105 



If the species be an advancing one, the record written in the seed will 

 show some infinitesimal step forward in that advance, or if the species 

 be dying out it will bear some trace of retrogression. 



A ripe seed is, to all appearance, as quiescent and lifeless as a stone. 

 This appearance, however, does not represent tbe truth. It is plain that 

 some continuous action goes on in the substance of the seed, and that 

 this action exhausts itself in process of time, for if the seed be kept dry 

 beyond a certain period it perishes. 



Much has been written upon the chemical and morphological changes 

 which take place during the germination of seed and the growth of the 

 plant, but very little upon the relation of these changes to the physical 

 or vital energy which is the cause of them. What is the dynamical 

 meaning of "growth?" Of the differentiation of leaf from stem, of 

 flower from leaf, of seed from flower ? When is a seed properly " ripe ?" 

 and what is its molecular condition when germination begins ? We can 

 follow the transformations of energy in the inorganic world from chemical 

 affinity into heat, from heat into mechanical work, from work into light 

 or electricity, and from these into heat once more ; can we not trace a 

 similar dynamical cycle in the changes of the living plant ? 



Theoretically a body in motion might, under certain conditions, 

 continue to move in a straight line with uniform velocity for ever. 

 Practically, however, this does not happen. All moving bodies encounter 

 resistance, and all velocities are perpetually changing. The result is 

 that all motions assume the character of the wave ; that is to say, they 

 have two points of minimum velocity or intensity, and an intermediate 

 point at which the velocity or intensity is at its maximum. There are 

 two principal forms of wave-motion, the undulatory and the concentric. 

 A living organism is the expression of a more or less complex concentric 

 wave of motion. 



In the dry, ripe seed, which lies for months or years without visible 

 motion, without sensible change of weight or temperature, the energy 

 which constitutes its life probably exists as atomic motion only, and is 

 concealed from our human senses because the movements of atoms 

 within the limits of their respective molecules do not affect the ether in 

 any way of which we are able to take cognisance. The seed is ripe when 

 this atomic motion has reached its maximum, and from that moment it 

 begins to be reconverted into molecular motion, and dissipated by 

 radiation. 



This conversion may be very slow, but it must terminate within 

 a definite time ; and, if the whole atomic energy is converted and 

 dissipated before the necessary conditions of germination are provided, 

 the seed perishes, and its molecules having lost the amount of energy 

 required for independent existence as an organic unit, are taken up by 

 Burrounding attractions and dispersed. But if, on the contrary, a supply 

 of energy is furnished to the seed externally before the exhaustion of its 

 internal store ; if heat is communicated to it, and such material as it can 



