512 THE PHYSIOLOGY OF REPRODUCTION 



In the placenta there is evidence of a transmission of fat to 

 the product of conception. Even in the early stages of preg- 

 nancy the cells of the uterine mucosa are infiltrated with fat, 

 and the trophoblast is pervaded with fat globules. In Ungu- 

 lates a large amount of fat is contained in the uterine milk 

 (see p. 403). In those mammalian orders, in which the tropho- 

 blast is directly bathed by maternal blood, the fat dissolved in 

 it forms a second available supply. There is no reason to doubt 

 an active transference of fat from the mother, or to assume that 

 a transformation from carbohydrates or proteins is necessary. 



c. The Daily Requirement of Fat for the Foetus. — The daily 

 requirement of fat varies very considerably during pregnancy, 

 and especially towards the end, when the subcutaneous fat of 

 the foetus is deposited. Fehling^ found 0-5 per cent, of fat 

 in the human foetus at the fourth month, over 4 per cent, at the 

 eighth, and 9 per cent, at the ninth month. 



d. Origin of ike Fostal Fat. — As to its origin, Thiemich ^ states 

 that it is not derived from the alimentary fat of the mother, 

 since after feeding a dog in two successive pregnancies on widely 

 different fats, pahnin and linseed oil, he could determine no 

 difference in the constitution of the foetal fat. Oshima * comes 

 to the same conclusion from his investigations on the number 

 of ultra-microscopic particles in the blood of cats, rabbits, and 

 guinea-pigs. He states that the number is dependent on the 

 stage of development, and independent of the condition of the 

 mother's blood — for example, when a great increase is produced 

 by rich fat-feeding. Capaldi, on the other hand, states that the 

 percentage of fat is the same in the maternal and foetal blood, 

 at least at the end of pregnancy. Some feeding experiments 

 carried out by Hofbauer * agree with this. He administered 

 coco-nut oil ® to three pregnant guinea-pigs, and demon- 



' Fehling, "Beitrage zur Physiologie des placentaren Stoffverkehrs," 

 Arch. f. Qyndk., vol. xi., 1877. 



" Thiemich, " Ueber die Herkunft des fotalen Fettes, Gentralhl. f. Phys., 

 vol. xii., 1898. 



' Oshima, "Ueber das Vorkommen von ultra-mlkrosoopisohen Tellohen 

 im fotalen Blute,!' Oentralhl. f. Phys., vol. xxi., 1907. 



* Hofbauer, Biologie der menschlichen Plazenta, Wien and Leipzig, 1905. 



^ It consists essentially of the triglycerides of laurinic and myristinic acids 

 with a very small quantity of tripalmitiu. 



