i2 4 SCIENCE PROGRESS 



Obviously the chance of an interchange of their products with 

 the surrounding medium, which is the very essence of life, will 

 be far greater in the single-celled organisms than in the multi- 

 cellular organism with its pipes and tubes. In the latter the 

 chance for accumulation of by-products and therefore the need 

 of a swift and effective neutraliser, like oxygen, will be corre- 

 spondingly greater. 



We seem to have here a simple picture why it is that the 

 oxygen-need should increase with complexity of organisation. 

 The differences shown by organisms, high and low, of about the 

 same grade of organisation would appear to be due to those 

 differences of chemical composition which present-day research, 

 especially the "biological" or precipitin action, have so amply 

 disclosed. 



IV. Anaerobiosis and the Biogenetic Law. — We may now put 

 the theory of anaerobic origins to what, in many minds at least, 

 is a crucial test. 



It seems to be fairly clear that every organism is in some 

 sense an historical document ] and that in a broad way the 

 development of every individual (ontogeny) reflects the history 

 of its race (phylogeny). This is the recapitulation 2 or " repeti- 

 tion " 3 theory or biogenetic " law," in Haeckel's phrase, 4 so long 

 discussed, so much disputed, which now seems in process of 

 being firmly grounded on bio-chemical experiment, 5 free from 

 the subjective idiosyncrasies which have so obviously begotten 

 the acrimonious controversies which this question has aroused, 

 although it is evident enough that we cannot regard it as a 

 " law " in any rigid sense. 6 



Likewise there are now few, even among biologists, who 

 doubt that the processes of growth have a chemical basis 7 and 



1 Cf. Boveri's fine essay, Die Organismen als Historische Wesen (Wurzburg, 

 1906). 



2 An admirable critical summary is Vailleton's Un problbne de l Evolution 

 (Paris, 1908). 



3 T. H. Morgan, Evolution and Adaptation, p. 58(N.Y. 1903). 



* For an excellent though partisan review, cf. H. Schmidt, Das Biogenetische 

 Grundgesetz (Frankfurt, 2te auf. 1909). 



5 E. Abderhalden, " Der Arten begriff," Naturw. Runds. 557, 19, 1904. 



6 Cf. L. Plate, Archiv f. Rassenbiol. 198 and 721,3, 1906; Weismann, Vorl. 

 u. Descendenztheorien, 179, II. 1902. 



7 F. Hofmeister, Die Chem. Org. d. Zelle, 1904 ; Hober, Physik. Chem. d. 

 Zelle, Kp. 15 ; G. Ciamician, La Chimica Organica negli Organismi (Bologna, 

 1908). 



