TRANSACTIONS OF SECTION I. 815 



12,000,000,000,000 organic molecules. TLe organic molecules we are considering 

 are suck as build up living matter, namely, proteids, fats, carbohydrates, saline 

 substances, and water. There is, however, no satisfactory evidence that they exist 

 as such in living matter, and it may be that they are formed when living matter 

 dies. Thus the molecule of living matter may be a much more complicated 

 molecule than even that of such a complex proteid as haemoglobin, so that it may 

 contain 10,000 atoms. But even if this were the case the fecundated ovum might 

 yet contain 1,200,000,000 of such complex molecules. Clerk Maxwell's argument 

 that there were too few organic molecules in an ovum to account for the transmission 

 of hereditary peculiarities does not apparently hold good. Instead of the number 

 of organic molecules in the germinal vesicle of an ovum numbering something like 

 a million, the fecundated ovum probably contains millions of millions. Thus the 

 imagination can conceive of complicated arrangements of these molecides suitable for 

 the development of all the parts of a highly complicated organism, and a sufficient 

 number, in my opinion, to satisfy all the demands of a theory of heredity. Such a 

 thing as a structureless germ cannot exist. Each germ must contain peculiarities 

 of structure sufficient to account for the evolution of the new being, and the germ 

 must therefore be considered as a material system. 



Further, the conception of the physicist is that molecules are more or less in a 

 state of movement, and the most advanced thinkers are striving towards a kinetic 

 theory of molecules and of atoms of solid matter which will be as fruitful as the 

 kinetic theory of gases. The ultimate elements of bodies are not freely movable 

 each by itself ; the elements are bound together by mutual forces, so that atoms 

 are combined to form molecules. Thus there may be two kinds of motion, atomic 

 and molecular. By molecular motion is meant ' the translatory motion of the 

 centroid of the atoms that form the molecule, while as atomic motion we count all 

 the motions which the atoms can individually execute without breaking up the 

 molecule. Atomic motion includes, therefore, not only the oscillations that take 

 place within the molecule, but also the rotation of the atoms about the centroid of 

 the molecule.' ' 



Thus it is conceivable that certain vital activities may be determined by the 

 motion that takes place in the molecules of what we speak of as living matter. 

 It may be different from some of the motions known to physicists, and it is con- 

 ceivable that in the state we call living there may be the transmission to dead 

 matter, the molecules of which have already a kind of motion, of a form of 

 motion sici r/e/ieris. The imagination fails to follow the possible movements of 

 molecules in a particle of living protoplasm. We cannot grasp the wondrous 

 spectacle of the starry heavens with its myriads of orbs all in motion, each motion 

 being rigorously determined. But if we could see into the structure of living 

 matter, we would find another universe of molecules in movement, and here again 

 we would also find the rigor of law. On the character and complexity of these 

 movements will depend the physical and chemical phenomena manifested by this 

 living matter. The cliemical irritability of living matter which is perhaps one 

 of its most remarkable characteristics, the rapid series of chemical exchanges 

 going on between its own parts and between itseif and the matter surrounding 

 it, the changes in surface tension, in elasticity, and the changes in electrical 

 condition, are all in some way associated with the movements of the molecules of 

 which it is constructed. It will only be when we have grasped the significance of 

 these molecular movements that we will be able to give a rational explanation of 

 the ultimate phenomena of the living state. Just as the physicists of to-day are 

 striving towards a dynamical conception of the phenomena of dead matter, so I 

 believe the physiologists of to-morrow (a far off to-morrow) will be striving 

 towards a dynamical conception of life founded on a molecular physiology. 



I offer these remarks with much diffidence, and I am well aware that much 

 that I have said may be regarded as purely speculative. They may, however, 

 stimulate thought, and if they do so they will have served a good purpose. Meyer 

 writes as follows in the introduction to his great work on ' The Kinetic Theory of 



' Meyer, Kinetio Theory of Gases, Translated by Baynes, London, 1899, p. 6. 



