THE PHYSICAL REDUCTIO AD ABSURDUM 215 



molecules of water, and that when the highly complex molecules 

 of the nucleo-proteins have a molecular weight of not less than 

 15,000, the number of protein molecules capable of occupying 

 this diameter must be very much smaller. But, in the opinion 

 of many modern physicists, this estimate of Lord Kelvin's repre- 

 sents if anything the maximum and not the minimum possible 

 size of a molecule of water. Nernst, indeed (Theoretical Chemistry, 

 translated by Palmer, pp. 348 et seq.), accepts Van der Waals' 

 calculation, based upon the molecular kinetic theory, that 

 the magnitude of the molecule (of water) is ^ millionth of a 

 micro-millimeter (0*000002 //,), or otherwise that along a line 

 0-5 fju in length there could exist not 150 but 2500 molecules of 

 water. Even taking this estimate, Weismann's conception is 

 still outside the limits of the possible, when the huge size of the 

 nucleo-protein molecule is taken into account as compared 

 with that of a simple molecule such as water. 



" If the biophores are, according to Weismann's conception, 

 not simple molecules of proteid type, but aggregations of the 

 same, the determinants, composed of aggregations of biophores, 

 should be recognizable under the highest powers of the micro- 

 scope, and the ' id ' formed in the higher animals of thousands 

 and ten thousands (of determinants) must inevitably be a body 

 of from 30 to 300 times the diameter of the determinant — so 

 large, that is, that if it existed it must have been recognized 

 from the moment the nucleus of the cell was first observed. 

 And if, as Weismann supposes, the nucleus of the ovum contains 

 hundreds of ids derived from numerous ancestors, that nucleus 

 would fill the whole field of the microscope ! Needless to say 

 this is not the case ; nor, we may add, does the coarseness of the 

 nuclear structure vary materially according to the complexity 

 of the animal. Physically, therefore, Weismann's conception 

 is an impossibility, and, as Weismann has carried the conception 

 of preformation to its logical outcome, it follows that in demon- 

 strating the impossibility of his theory we simultaneously destroy 

 all less fully developed theories of preformation. 



" Determinants, in Weismann's sense, cannot exist." *] 



1 [And this despite Professor Arthur Thomson's inability to entertain the 

 view that it is possible to dispense with any postulate of "Representative 

 particles " {Heredity, 1912, p. 454).] 



