So6 THE PHYSIOLOGY OF REPRODUCTION 



that at first the hsemoglobin derivatives are in too firm combination 

 to take on the stain, then they are farther broken down and stained 

 granules appear, and later they are again synthesised into non- 

 stainable compounds which reach the foetal circulation. Such 

 changes were characteristic of the first half of pregnancy. In the 

 second half the iron-reaction of the villi was " extraordinarily slight." 

 Iron is stored in the liver and other foetal organs. According to 

 Bunge,^ it diminishes rapidly after birth, and he supposes that it 



compensates for the insufficient amount of 

 iron contained in the mammary secretion. 



Albumen 



The transmission of albumen to the 

 foetus of the rabbit has already been referred 

 to (see p. 464). In the human placenta 

 attention has been chiefly directed to the 

 investigation of the decomposition products 

 of proteins. Matthes^ and Hofbauer state 

 that albumoses are present in the placenta, 

 Ijut this is doubtful. In watery extracts 

 Eielander ^ demonstrated purine bases, uracil 

 and choline, and in the autolysed placenta 

 leucine ancl tyrosine have been found 

 (Basso*). It is generally held that such 

 results prove an active metabolism of pro- 

 tein in the foetal placenta. 



Fig. 157. — Iron granules 

 in a villus of the 

 placenta in man. 

 (From Hofbauer's 

 Biologie der mensoh- 

 lichen Plazenta, Brau- 

 miiller.) 



Creatin and' Creatinine 



Hunter and CampbelP have investigated 

 the concentrations of creatin and creatinine 

 in the foetal and maternal blood. Their 

 method was to take a sample of blood from 

 the placental end of the umbilical cord as soon as it was cut and at 

 the same time from the arm vein of the mother. They found a very 

 slightly higher concentration in the foetus. They conclude that the 

 placental transmission of creatin and creatinine is a simple process of 

 diffusion. 



' Bunge, "Ueber die Aufnahme des Eisens in den Organismus des 

 Sauglings," Zeitsch. f. phys. Chem., vol. xvii., 1893. 



^ Matthes, " Ueber Autolyse der Placenta," Gentralbl. f. Ch/ndk., 1901. 



^ Rielander, "Ein Beitrag zur Ohemie der Placenta," Gentralbl. f. Gryndk., 

 1907. 



* Basso, " Ueber Autolyse der Placenta," Arch. f. Oynak., vol. Ixxvi. 



* Hunter (A.) and Campbell, " The Placental Transmission of Creatinine and 

 Creatin," Jour, of BioL Chem., vol. xxxiv., 1918. 



