SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 



771 



Rosenthal S^Lasnibski 

 (Rat) 

 ver kidney 

 • ♦ NGR 



O OGR 



It would seem, therefore, that Hawkins is not very wide of the mark 

 when he suggests that N.G.R. is a function of growth-rate. He 

 believes that tissues can be classified better in this way than by using 

 R.R. and O.G.R. relationships as the German school does. 



Kumanomido also made a few experiments with the chorion of 

 hen and rat embryos and with rat embryos themselves, finding in all 

 cases that the N.G.R. was higher in Ringer solution than in serum. 

 He examined a few normal human chorionic membranes and 

 placentas, and obtained a very low N.G.R. (of about 5). There 

 was here a certain contradiction 

 between his results and those 

 of Murphy & Hawkins, who 

 worked with rat placentas, and 

 got the results shown in Table 9 1 . 

 However, neither of these papers 

 contain details of the age of the 

 placentas used, though from 

 Kumanomido's description it 

 would seem that he used full- 

 term material. Murphy & Haw- 

 kins' paper was mostly con- 

 cerned with the in vitro respira- 

 tion and glycolysis of various 

 types of neoplasm, but they con- 

 firmed the results of Warburg, 

 Posener & Negelein on the chick embryo, and stated that the same type 

 of respiratory metaboHsm was shown by rat embryo skin, rat embryo 

 membranes, and the wall of the pregnant rat uterus, although they 

 gave no figures in support of this. 



The most illuminating suggestion as regards the placenta in this 

 connection is that of Bell, Cunningham, Jowett, Millet & Brooks, 

 who found, as is shown in Table 9 1 , that the early human placenta 

 gave a positive U., i.e. possessed on the whole a more active glycolytic 

 than oxidative mechanism. Then, removing the chorionic epithelium, 

 they made the experiment again, and found that the result was now 

 a negative U. like that given by practically all non-neoplasmic tissues. 

 They therefore did not hesitate to regard the penetration of the 

 maternal tissue by the invading foetal trophoblast as truly "malig- 

 nant", a standpoint of much interest from several points of view 



2 34 5 6 78 9101112 1 

 cms. length of body Adult 



Fig. 176. 



