2 6 BIOLOGICAL LECTURES. 



compelled to deny on the ground of the organization of the egg 

 itself. Nor is it possible to deny the reciprocal effects of cells 

 upon each other ; the parts are reciprocals of the whole, as the 

 latter is reciprocal to a part. The organism during every 

 phase of its existence is a molecular mechanism of inconceiva- 

 ble complexity, the sole motive force of which is the energy 

 that may be set free by the coordinated transformation of 

 some of its molecules by metabolism. An appeal to anything 

 beyond this and the successive configurations of the molecular 

 system of the germ, as a whole, resulting from the changing 

 dynamical properties of its molecules, as their individual con- 

 figurations and arrangement change, must end in disappoint- 

 ment. We must either accept such a conclusion or deny that 

 the principle of the conservation of force holds in respect to 

 the behavior of the ultimate molecular constituents of living 

 substance. But to deny that that principle is operative in 

 living creatures is to question direct experimental evidence to 

 the contrary, since Riibner has been able to actually use an or- 

 ganism as a fairly accurate calorimeter. 



The initial configuration or mechanical arrangement and suc- 

 cessive rearrangements of the molecules of a germ, the addition 

 of new ones by means of growth, plus their chemical and 

 formal transformation as an architecturally self -adjusted aggre- 

 gate, by means of metabolism, is all that is required in an 

 hypothesis of inheritance. The other properties of living 

 matter, such as its viscosity, free and interfacial surface-ten- 

 sion, osmotic properties, its limit of saturation with water, its 

 segmentation into cells, in short, its organization, must be the 

 result of the operation of forces liberated by its own substance, 

 during its growth by means of metabolism. We cannot ex- 

 clude external forces and influences, such as chemism, light, 

 heat, electricity, gravity, adhesion, exosmosis, food, water, air, 

 motion, etc., in the operation of such a complex mechanism. 

 It is these agencies that are the operators of the living mech- 

 anism, which in its turn makes certain successive responses in 

 a way that is determined within limits by its own antecedent 

 physical structure and consequent dynamical properties. The 

 parts of the whole apparatus are kept in a condition of con- 



