22 BIOLOGICAL LECTURES. 



acteristic of living matter, namely, the large and relatively 

 fixed amount of water it contains, and also the mobility of its 

 molecules in respect to one another; its jelly-like character at 

 one instant ; its fluidity and power of motion at another. It 

 is indeed probable that the amount of water contained in living 

 matter is controlled within certain limits by the forces of 

 cohesion exerted between adjacent molecules against the 

 osmotic pressure or capillary action of water tending to drive 

 them asunder, as supposed by Nageli, in his hypothesis of 

 micellae. Such an hypothesis enables us to explain much that 

 is otherwise quite unintelligible in relation to living things. 

 It renders us an explanation of amoeboid motion, of the surface 

 tensions of protoplasm and lastly of metabolism itself through 

 osmosis and the specific characters of the chemical transforma- 

 tions that must take place in each kind of living substance. 



Such an hypothesis may also afford us mechanical construc- 

 tions of atoms, grouped into very large rn^tajn^nc^r^rjpjyjn^rj.p 

 molecules of the utmost diversity of powers, capable of under- 

 going a long series of successive transformations, so as to 

 manifest in the long run, starting with a molecular germinal 

 aggregate, what we call ontogeny or development. These 

 transformations, we must suppose, are effected by the metab- 

 olism incident to growth, and moreover, that starting with an 

 initial configuration of a system of molecules, as a mechanical 

 and consequently a dynamical system of determinate powers, 

 in the form of a germ, it cannot undergo any other transforma- 

 tions except such as lead to an approximate recapitulation of 

 the ancestral development or phylogeny. This supposition 

 follows from the rule that must hold of determinate systems 

 of molecules, as well as of systems formed of larger masses, 

 namely, that the initial changes in the configuration of such a 

 complex system must dynamically determine within certain 

 variable limits, under changing conditions, the nature of all of 

 its subsequent transformations, including those due to growth 

 and consequently increased complexity. We thus escape the 

 necessity of invoking certain "proclivities" of physiological 

 units, or the necessity of appealing to the growth and fission of 

 "biophors" or the scattering of "determinants" at the proper 



