126 SCIENCE PROGRESS 



development. The embryo will have less need relatively of 

 oxygen than the adult and this need will increase parallel with 

 the growth of the organism. What now are the facts ? 



W. Roux and Jacques Loeb were among the first to investi- 

 gate this question. Roux found that the eggs investigated by 

 him were incapable of development in the complete absence of 

 oxygen and soon disintegrated. This result was confirmed in 

 part by Loeb, 1 who, however, found that among the eggs of 

 various animals there is a wide disparity in this respect. Thus 

 for example, the eggs of surface-swimming animals are very 

 sensitive to the absence of oxygen, whilst in those whose density 

 is sufficient to cause them to sink the oxygen need is enormously 

 reduced. So for example, the eggs of Fundulus continued to 

 divide during twenty-four hours in an oxygen vacuum and during 

 twelve hours in a current of hydrogen. 



But what was more important still, Loeb established the 

 fact that " the embryo is the more sensitive to a lack of oxygen 

 the older it is." Thus an egg put into an oxygen vacuum twenty- 

 four hours, thirty-six hours, etc., after fertilisation was corre- 

 spondingly less resistent to this withdrawal. So in turn the 

 newly-born fish was still less resistent than the embryo (I.e.). 



This general law established by Loeb, that the need of 

 oxygen is inversely proportional to age (i.e. size) has been 

 further extended and confirmed through the researches of 

 H. Samassa, E. Godlewski and K. Amerling for animals and by 

 W. Palladin and O. Nobokich especially for plants. 



Samassa 2 found and Godlewski 3 in a series of researches 

 confirmed the fact, that frogs' eggs continued to divide during 

 twenty hours after fertilisation in the complete absence of 

 oxygen. Compare now this result with the experiments of 

 Amerling 4 on the larvae of frogs at different periods of develop- 

 ment. The latter took as his test the time which elapsed 

 before the larvae showed distinct signs of cessation of their 

 normal activities (Lahmung). His results are shown in the 

 following table : 



1 "U. d. Empfindl. v. Fischemb. geg. Sauerstoffmangel in versch. entw. Stadien," 

 Pftueger'sArchiv, 530, 55, 1894 ; "Unt. u. d. physiol. Wirkungend. Sauersmangels," 

 ibid. 249, 62, 1896. 



2 Verh. d. deut. Zool. Gesell. 1896. 



3 Archivf. Entw. 585, 11, 1901 (for full literature). 

 * P flue iter's Archiv, 369, 121, 1908. 



