SECT. 8] CARBOHYDRATE METABOLISM 1019 



The conception of a late development of the glycogenic function 

 of the liver is no new one. In 1858 Claude Bernard published his 

 researches on mammalian embryos, in which he clearly showed that 

 the glycogenic function later to be undertaken by the liver was, during 

 the greater part of foetal life in mammals, carried out by the placenta. 

 On p. 120 he wrote in a footnote, "Dans les oiseaux (poulet) j'ai 

 constate, avant le developpement des cellules glycogenes du foie, 

 I'existence de cellules glycogenes qui se developpent dans les parois 

 du sac vitellin ; mais n'ayant pas pu suivre encore completement leurs 

 evolutions, je traiterai ce sujet dans une autre communication, me 

 bornant aujourd'hui a parler des mammiferes". This promised re- 

 search was delayed for six years owing to Bernard's illness. On 

 March 31, 1864, he deposited a "pH cachete" at the Academic des 

 Sciences, in which he stated that he had shown the presence of 

 glycogen in the blastoderm of the chick, and regarded it as com- 

 parable, from this point of view, with the placenta of mammals. 

 Moreover, he had isolated the glycogen from the blastoderm and 

 identified it chemically, obtaining from it alcohol and carbon dioxide 

 by appropriate fermentation. In 1872 Bernard read a full account of 

 subsequent experiments before the Academy, and caused his sealed 

 communication to be opened and read. His own words may be 

 quoted, "4 Juin i860. Sur un oeuf de poule du deuxieme au troisieme 

 jour d'incubation, j'ai detache avec des ciseaux la membrane vitelline 

 tout autour de I'area vasculosa; je I'ai enlevee avec des pinces de 

 maniere a appliquer sa face exterieure contre une lame de verre. En 

 examinant ensuite sous le microscope cette preparation, j'ai vu tres 

 nettement des cellules glycogeniques et des granulations de glycogene 

 qui prenaient une couleur rougeatre par la teinture d'lode acidulee 

 avec I'acide acetique crystallisable". Bernard concluded that the 

 blastoderm contained a notable store of glycogen for the needs of the 

 embryo. He afterwards published a full account of his work in this 

 field in his masterly Legons sur les phenomenes de la vie. 



It will be convenient here to discuss birds and mammals indis- 

 criminately with reference to what Claude Bernard called the pheno- 

 menon of the "foie transitoire " or temporary liver. Bernard described 

 in detail the histological appearances of the placenta when stained to 

 show glycogen, but he did not rely solely on histochemical observa- 

 tions, for he mentioned the results of several chemical experiments 

 which led to the same conclusion. " II existe en effet, " said Bernard, 



