96 ACTION OF LIGHT RAYS 



poisonous to such living organisms, and when produced nascently 

 by the action of sunlight, or ultra-violet light, and probably at 

 selective concentrations on interfaces, it is quite probable that the 

 death of the whole organism might so be induced. The action of 

 the light would be progressive upon the living cell just as it is within 

 quartz containers upon the more complex organic substances, and 

 would manifest itself in a continuous hydrolysis of the more con- 

 jugated to less conjugated substances. The first effect would be 

 upon the state of colloidal aggregation of the system, but con- 

 currently formaldehyde and other organic compounds of simple 

 type would be set free. 



It is noteworthy that formaldehyde and other simple related 

 substances, such as would be the first stages in the evolution of the 

 organic from the inorganic, are all highly poisonous to the much 

 later product in evolution namely, the living organism. Such 

 simple substances are formaldehyde, formic acid, oxalic acid, hydro- 

 cyanic acid, methylic and ethylic alcohols, hydrogen peroxide, 

 and the simpler nitrites and nitriles; all these are poisonous to 

 the highly organised and labile colloids of the bioplasm, and 

 probably on account of that very property which makes them 

 essential in the first stages of organic evolution namely, their 

 high reactivity and the ease with which they take part in additive 

 reactions of organic substances. For this reason they must 

 undergo change in any living cell whilst still at high dilution, 

 or else they so interlock into the labile system of organic 

 colloids within the cell as to clog all metabolic change. Hence 

 it is that the energy of light, which is essential to healthy 

 growth and the upbuilding of organic material from inorganic, 

 supplied in a wrong fashion and not shielded in its onset, may reverse 

 these delicate processes and cause death and degeneration of living 

 substance, instead of being the potent agency towards building up 

 fresh material. 



The subject is one of enormous and far-reaching importance. 

 Blue light is the most universal and potent natural purifier of our 

 oceans and streams and our supplies of drinking-water. Light is 

 also the agency which in spring, when the sun attains a certain 

 altitude and less of the actinic light is absorbed by the atmosphere, 

 penetrates the water of the ocean and lakes in sufficient intensity to 

 stimulate the great outburst of vegetable plankton, which initiates 

 the long sequence of swarms of animal life up to the fishes, and sup- 



