448 ON GENERATION. 



viviparous animals are developed, and at the same time de- 

 monstrate that these all derive their origin from eggs, and live 

 by a twofold albuminous food in the womb. One of these is 

 thinner, and contained within the ovum or conception; the 

 other is obtained by the umbilical vessels from the placenta 

 and uterine cotyledons. The fluid of the ovum resembles 

 a dilute albumen in colour and consistence ; it is a sluggish, 

 pellucid liquid, in all respects similar to that which we have 

 called the colliquament of the egg, in which the embryo swims, 

 and on which it feeds by the mouth. The fluid which the 

 foetus obtains from the uterine placenta by the aid of the um- 

 bilical vessels is more dense and mucaginous, like the inspis- 

 sated albumen. Whence it clearly appears that the foetus in 

 utero is no more nourished by its parent's blood than is the 

 suckling afterwards, or the chick in ovo ; but that it is nou- 

 rished by an albuminous matter concocted in the placenta, and 

 not unlike white of egg. 



Nor is the contemplation of the Divine Providence less 

 useful than delightful when we see nature, in her work of 

 evolving the foetus, furnishing it with sustenance adapted to 

 its varying ages and powers, now more easy, by and by more 

 difficult of digestion. For as the foetus acquires greater powers 

 of digesting, so is it supplied with food that is successively 

 thicker and harder. And the same thing may be observed in 

 the milk of animals generally : when the young creature first 

 sees the light the milk is thinner and more easy of concoction ; 

 but in the course of time, and with increased strength in the 

 suckling, it becomes thicker, and is more abundantly stored 

 with caseous matter. Those flabby and delicate women, there- 

 fore, who do not nurse their own children, but give them up 

 to the breast of another, consult their health indifferently ; for 

 mercenary nurses being for the major part of more robust and 

 hardy frames, and their milk consequently thicker, more 

 caseous, and difficult of digestion, it frequently happens that 

 milk of this kind given to the infants of such parents, parti- 

 cularly during the time of teething, is not well borne, but 

 gives rise to crudities and diarrhoeas, to griping, vomiting, 

 fever, epilepsy, and other formidable diseases of the like nature. 



What Fabricius says, 1 and strives to bolster up by certain 



1 Op. cit. p. 34. 



