ON GENERATION. 451 



wondered at both in the yelk and the white, viz. that neither of 

 them being blood, they are still so near to the nature of blood 

 that they in fact differ but very slightly from it there is but 

 little wanting to constitute either of them blood ; so that little 

 labour and a very slight concoction suffice to effect the change. 

 The veins and arteries distributed to the membranes of both 

 the white and yelk are consequently seen replete with blood at 

 all times ; the white and yelk nevertheless continuing possessed 

 of their own proper nature, though either, so soon as it is im- 

 bibed by the vessels, is changed into blood, so closely do they 

 approach in constitution to this fluid." 



But if it be matter of certainty that blood exists no less in 

 the vessels distributed to the albumen than in those sent to 

 the vitellus, and that both of these fluids are so closely allied 

 to blood in their nature, and turn into blood so readily; who, 

 I beseech you, will doubt that the blood, and all the parts 

 which are styled sanguineous, are nourished and increased 

 through the albumen as well as the vitellus? 



Our author, however, soon contrives a subterfuge from this 

 conclusion : " Although all this be true," he says, 1 " still must 

 we conceive that the matter which is imbibed by the veins 

 from the yelk and white is only blood in the same sense as the 

 chyle in the mesenteric veins, in which nothing but blood is 

 ever seen; now chyle is but the shadow of blood, and is 

 first perfected in the liver; and in like manner the matter 

 taken up by the veins from the white and yellow is only the 

 shadow of blood/' &c. Be it so ; but hiding under this sha- 

 dow, he does not answer the question, wherefore the blood and 

 blood-like parts should not, for the reasons cited, be equally 

 well nourished by the albumen as by the vitellus ? 



Had our author, in like manner, asserted that the hotter 

 parts are rather nourished by that blood which is derived from 

 the vitellus than by that attracted from the albumen, and the 

 colder parts, on the other hand, by that which is derived from 

 the albumen, I should not myself have been much disposed to 

 gainsay him. 



There is one consideration in the whole question, however, 

 which is sorely against him; it is this how is the blood 



1 Op. cit. p. 55. 



