TRANSFORMISM 251 



there are included a multitude of small, independent, contributory 

 causes which lead to a certain statistical result, but also to a 

 number of " accidental " variations from that result. The 

 developmental agency manifests itself (just as the ideal minting 

 machine does) in the assemblings of material-energetic things 

 and the fluctuations are in these assemblings of chemical 

 substances and energy-transformations. 



85c. Mutations Regarded as very Improbable Fluctua- 

 tions. Again we approach this problem from the purely physical 

 view-point. Let there be a physical-chemical system of OH 2 

 and CO 2 molecules with light radiation impinging on these 

 individuals. They are " energized," that is, they move with a 

 certain mean velocity, but there will be some molecules that move 

 with velocities much greater than this mean. Let the frequency 

 of the incident radiation increase and it may happen that a few 

 of the CO 2 and OH 2 molecules become highly energized so that 

 they move with greatly increased velocities, or their internal 

 (electronic) energies become greatly increased. We may regard 

 such " super-energized " molecules as very exceptional, or im- 

 probable fluctuants. They may, in this highly energized condition, 

 then combine to form formaldehyde — which, in a way, may be 

 thought about as a chemical mutation. Again the molecules of 

 yellow phosphorus have, in that phase, mean energy-values and 

 there are in the multitude of molecules that make up a small 

 mass of the substance, some that fluctuate much above this mean 

 in energy- value. Let the phosphorus be heated out of contact 

 with oxygen to a certain temperature and these exceptional 

 fluctuants greatly increase in number and in energy. The 

 phosphorus then undergoes transformation into its red, allotropic 

 modification — that is, a chemical mutation has been effected. 



Something analogous to this occurs when mutations are 

 '* induced " in organisms. Thus the eggs and larvae of some 

 animals may develop in unusual ways when the pregnant parents 

 are exposed to temperatures, or other physical conditions, that 

 are very exceptional but are not so exceptional as to kill the 

 animals. Drosophila, which is bred, for experimental purposes, 

 in highly artificial conditions has been fertile in displaying muta- 

 tions. Certain goldfishes reared in small aquaria, in rather 

 stagnant water, give curious mutations. Generally domesticated 

 plants and animals are bred and reared in conditions differing 



