430 Harvey's Ideas o£ Embryonic Nutrition 



tive juice might be as readily transported by the uterine arteries, and distilled 

 into the uterus, as watery fluid is carried -by the emulgent arteries to the kid- 

 neys . . . What you say of the excrements of new-born infants differing from 

 those of the child that has once tasted milk I do not admit . . ." (p. 614-615). 



Harvey began his discussion "of the nutrition of the chick in ovo," in "Ex- 

 ercise the Fifty-eighth" of the De Generatione, by recalling that Democritus, 

 Epicurus, and Hippocrates supported the idea that the mammalian foetus 

 sucks in utero. He said that his teacher, Fabricius, had rejected this idea "as a 

 delusion," but that he nevertheless believed it because his observations on 

 generation make that opinion not "merely probable" but necessary. In support 

 of his opinion Harvey further called attention to the "fact" that the amniotic 

 fluid ". . . has a pleasant taste, like that of watery milk, so that almost all 

 viviparous animals lap it up, . . . greedily swallowing" it (p. 435).* "To me, 

 therefore, the opinion of Hippocrates appears more probable than that of 

 Fabricius and other anatomists, who look on this liquid as sweat, and believe 

 that it must prove detrimental to the foetus. I am disposed, I say, to believe 

 that the fluid with which the foetus is surrounded may serve it for nourish- 

 ment; that the thinner and purer portions of it, taken up by the umbilical 

 veins, may serve for the constitution and increase of the first formed parts 

 of the embryo; and that from the remainder or the milk,-j- taken into the 

 mouth by suction, passed on to the stomach by the act of deglutition, and 

 there digested or chylified, and finally absorbed by the mesenteric veins, the 

 new being continues to grow and be nourished. I am the more disposed to take 

 this view from certain not impertinent arguments, which I shall proceed to 

 state. 



"As soon as the embryo acquires a certain degiee of perfection it moves its 

 extremities, and begins to prove the actions of the organs destined to locomo- 

 tion. Now I have seen the chick in ovo, surrounded with liquid, opening its 

 njouth, and any fluid that thus gained access to the fauces must needs have 

 been swallowed; for it is certain that whatever passes the root of the tongue 

 and gains the top of the oesophagus, cannot be rejected by any animal with 

 a less effort than that of vomiting. ... If the embryo swimming in the fluid 

 in question, then, do but open his mouth, it is absolutely necessary that the 

 fluid must reach the fauces; and if the creature then move other muscles, 

 wherefore should we not believe that he also uses his throat in its appropriate 

 office and swallows the fluid? 



* Even as late as 1815, Beclard, on the basis of experimental evidence, concluded that the 

 fetuses of mammals swallow amniotic fluid because hairs were present in the meconium of 

 fetuses whose necks had been constricted by a tourniquet. Beclard also had found hairs in a 

 still born proximal to the site of an intestinal obstruction, and had noticed that the increase 

 in the rapidity of fetal respiratory movements was proportional to the extent of placental 

 detachment. Moreover, pigment injected into the amniotic fluid, after ligation of the fetal 

 neck, was found up to the ligature. 



fThe word milk was then used to designate the fluids surrounding the fetus instead of 

 those within the uterus, but Harvey also spoke of milk in the thymus and lymph glands. 



