550 



Mr. Lee on the Functions of 



[Dee. 22, 



duodenum are most numerous, and that they dimmish towards the lower 

 portion of the intestine ; so that they are in greatest number where the 

 intestine contains most nutritive substance. 



" From this examination/' the author continues, " no further proof is 

 required that digestion and absorption are performed, as Harvey beheved, 

 during foetal Ufe. 



*'Tlie origin of the albuminous substance in the intestine was supposed 

 by Harvey to be the liquor amnii, which he attempts to prove is swallowed 

 by the foetus in utero. 



" In the Bird, as will be seen, the origin of this albuminous substance 

 was ascribed by John Hunter to the yelk-sac. 



In the year 1829 it was shown by Dr. Robert Lee, in a paper pub- 

 lished in the Philosophical Transactions, * On the Functions of the Foetal 

 Liver and Intestines,' that Harvey's explanation was not correct, and that 

 there is satisfactory evidence to prove that the Liver is the source of this 

 albuminous substance." 



In the foetal bird on the twelfth day of incubation, or later, " the liver 

 is seen to occupy both sides of the abdomen, as in the human foetus. The 

 yelk-sac is seen fixed to the small intestine ; the white more than half 

 absorbed. The umbilical vein receives blood from the chorion membrane, 

 in which it has been exposed to the influence of the oxygen of the atmo- 

 sphere ; it receives blood also from the yelk-sac and from the white. So 

 that the nature of the blood in the portal vein of the foetal bird is both 

 highly nutritious and arterial in character. 



" The intestines are in the same condition as in the human foetus. 



" The origin of the albuminous substance may be ascertained to be from 

 the same organ, namely, from the liver. 



" That John Hunter was mistaken in supposing that albumen passed 

 through the vitelline duct (that part of the yelk-sac which is connected 

 with the intestine), is generally allowed ; and his supposition may be almost 

 disproved by the fact that it is not possible to inject any fluid into the 

 yelk-sac from the intestine. Besides, Hunter states that it passes through 

 only at the time of hatching, which is not the case, as the intestines 

 are full long before the bird is hatched. The lacteals of the foetal bird 

 cannot be seen. 



To take another class of animals, the Marsupialia. The liver in the 

 foetal kangaroo at the time of birth (that is, in the sixth week of utero- 

 gestation), in the words of Professor Owen, * consisted of two equal and 

 symmetrically diposed lobes' (Art. * Marsupialia,' Cyclopsed. Anat. and 

 Physiology). As soon, however, as the mode of life is changed and the 

 umbilical vein closed, the liver begins to diminish in size. Yet there is 

 this resemblance between a Marsupial animal five or six months old, and 

 a human foetus of the same age in utero, that, although the source of 

 nutrition is different, yet the intestines are supplied with nutritive sub- 

 stance, and digestion proceeds in both cases alike, the nutritive substance 



