February 17, 1905.] 



SCIENCE. 



247 



pears that wheu the proteids are digested 

 by any organism they break down into 

 these fragments, of one sort and another, 

 the amido-acids, the amides, etc., which 

 may be put together again in new form to 

 constitute the peculiar proteids of that par- 

 ticular organism. We may thus get one 

 proteid out of any other by the breaking 

 up of the complex molecule and the rear- 

 rangement of its constituent fragments. 

 This fragmentation is readily accomplished 

 by the proteolytic enzymes, which probably 

 act on these bodies as the diastases do on 

 carbohydrates. 



oxroATiON. 



The second important line of progress 

 has been in the study of the oxidation of 

 carbon compounds at low temperatures. 

 For our purpose the important facts which 

 have only recently been developed are that 

 the oxygen of the air does not combine 

 directly with carbon or with carbon mon- 

 oxide to form COo or with hydrogen to 

 form H2O, as has heretofore been supposed. 



As long ago as 1893 Dixon's researches* 

 on explosive gases showed that molecular 

 oxygen was by far the most effective of the 

 atmospheric gases in retarding combiistion. 

 This surprising result could not be inter- 

 preted then, and only in the light of 

 Traube's theory and the studies of Bone 

 and others f on the oxidation of gases like 

 methane and ethane at low temperatures 

 has it been possible to picture the mechan- 

 ism of such combustion. This has been 

 (tone by Armstrong, J who (with Traube) 

 claims that the substances do not undergo 



"'The rate of e.xplosion in gases.' Phil. Trans. 

 Roy. Soc. London A. 184: 07-188. 1893. 



t Bone and Wheeler, ' The slow oxidation of 

 methane.' Trans. Chcm. Soc. London 81: 535-545. 

 1902; 84: 1074-1087. 1903. Bone and Stockings, 

 'Slow combustion of ethane.' Trans. Ghem. Soc. 

 London 85: 693-727. 1904. 



J ' Retardation of combustion by oxygen.' Ghem. 

 A" ('ICS 90: 25. 1904. 'Mechanism of combustion.' 

 Trans. Chcm. Soc. London 83: 1088. 1903. 



direct oxidation, but hydroxylation, i. e., 

 its hydrogen atoms are successively re- 

 placed by hydroxyl radicles, with conse- 

 quent splitting into various intermediate 

 products, such as carbon monoxid and 

 hydrogen peroxid, carbonic acid and water 

 being the end products. Armstrong says: 



There is little reason to suppose that changes 

 take place at high temperatures in rapid combus- 

 tions in ways very different from those in which 

 they occur at lower temperatures. * * * The 

 eflective operation is not the mere blow due to im- 

 pact or the vibration caused by this in the mole- 

 cule, but the conjunction of compatible mole- 

 cules and the consequent formation of composite 

 systems within which change can occur. In so 

 far as temperature influences the formation of 

 compatible systems, either as regards their char- 

 acter or tlie rate at which they arise, temperature 

 has an influence, but probably not otherwise. 



I ask you to notice, then, that the process 

 of combustion is now being interpreted in 

 the light of changes like those which have 

 long been known in organisms under the 

 name of hydrolysis, and are the character- 

 istic mode of action of enzymes. Thus, 

 when starch is acted upon by diastase it is 

 probably by repeated reactions between 

 water, dissociated into hydrogen and hy- 

 droxyl groups, and oxygen, in other words 

 by continued hydroxylation that it becomes 

 ready to fall apart into a series of dextrines 

 and finally into maltose. Diastase in some 

 way facilitates this dissociation. Maltase 

 takes up the task, and maltose, further 

 hydroxylized, cleaves into two molecules of 

 glucose. Then zymase may lend its aid 

 and hydrolyze the glucose molecule into 

 lactic acid, breaking the latter still further 

 into carbon dioxid and alcohol. 



The mechanism of the digestion of starch 

 is not known in detail, though the various 

 intermediate products have been fairly well 

 studied. The usual assumption made is 

 merely that water combines with the starch 

 under the action of diastase. I have car- 

 ried the theory a little further into detail, 



