LIFE WITHOUT OXYGEN 125 



that the structural and morphological differences between species, 

 classes and orders are in the end the expression of definite 

 chemical differences. 1 This is clear enough from various con- 

 siderations : from the fact that the haemoglobin of different 

 species crystallises in different systems ; from the production of 

 a vast variety of distinct chemical substances, as for example, 

 the organic acids, some of which are characteristic of a given 

 species ; and from many similar considerations but above all 

 from the wondrous development of blood- and serum-chemistry, 

 revealing as this does the most curious affinities, antagonisms, 

 differences and degrees of differences among the different 

 types. 2 



If this be true broadly, for racial characteristics, that is to 

 say for evolution in general, it must be true in greater or less 

 degree for each individual organism. 3 The latter must present 

 a corresponding chemical evolution through the different stages 

 of its life ; and for this there is a considerable and constantly 

 increasing evidence. 4 Just as, for example, certain of the vital 

 enzymes appear only at certain definite stages of development, 

 as the lab ferments in the second month of fcetal life in the 

 human organism, diastase in the third month succeeding birth, 5 

 etc., so in the ripened fruit are certain chemical substances which 

 are not to be found in the leaf nor the stem nor the root nor the 

 seed. 6 



Upon all this we might base a reasonable expectation that if, 

 in the evolutionary scale, we find an increasing need of oxygen 

 corresponding to an increasing complexity of structural and 

 chemical organisation ; if in other words primitive life is 

 anaerobic and ordinary aerobic respiration represents an evolu- 

 tion from this fundamental form ; and if, further, the recapitulation 

 theory holds good, we shall find all this mirrored in individual 



1 Hiippert, Erhaltung der Arteigenschaften (Prag, 1896) ; F. Hamburger, 

 Arteigens. und Assimilation (Leipzig, 1903) ; A. Gautier, Variation des Races et 

 des Especes (Paris, 1901). 



3 G. H. Nuttall, Blood Immunity and Blood Relationship (London, 1904) ; 

 Uhlenhuth, Beiheft. z. Med. Klinik. Heft 9, 1907 ; H. Friedenthal, Arbeit aus 

 exp. Physiol. 1908. 



3 Cf. V. Ducceschi, Evoluzione Morfologica ed Evoluzione Chimica (Bologna, 

 1904). 



4 H. G. Wells, Trans. Chicago Path. Soc. May r, 1909. 



5 F. Hamburger, I.e. ; Oppenheimer, Die Fermente, 3te auf. Spec. Th. 1909. 



6 Cf. the researches of Bigelow and Gore, U.S. Dept. of Agric. Bureau of Chem. 

 Bulls. Nos. 94, 97, 1905. 



