xiv CONTENTS. 



PAGE 



Of twin-bearing eggs .268 



Certain deductions from the preceding history of the egg . . . 270 



Of the nature of the egg ib. 



The egg is not the product of the uterus, but of the vital principle . 279 



The egg is not produced without the hen 284 



Of the manner, according to Aristotle, in which a perfect and fruitful egg 



is produced by the male and female fowl . 287 



Of the uses of this disquisition on fecundity 291 



The egg is not produced by the cock and hen in the way Aristotle would 



have it 293 



Nor in the manner imagined by physicians 294 



The male and the female are alike efficient in the business of generation . 296 

 Of the matter of the egg, in opposition to the Aristotelians and the medical 



writers .297 



In how far is the fowl efficient in the generation of the egg, according to 



Aristotle ? And wherefore is the concurrence of the male required ? 300 



The perfect hen's egg is of two colours . 303 



Of the manner in which the egg is increased by the albumen -. . . 305 

 Of what the cock and hen severally contribute to the production of 



the egg 307 



Of the cock and the particulars most remarkable in his constitution . 309 



Of the hen 313 



Of the sense in which the hen may be called the " prime efficient :" and of 



her parturition 318 



Of the manner in which the generation of the chick takes place from the egg . 323 



In how many ways the chick may be said to be formed from the egg . 325 

 Fabricius is mistaken with regard to the matter of the generation of the 



chick in ovo 327 



What is the material of the chick, and how it is formed in the egg . 333 

 Of the efficient cause of the generation of the chick and foetus . . .340 

 Of the manner in which the efficient cause of the chick acts, according io 



Aristotle 344 



The opinion of Fabricius on the efficient cause of the chick is refuted . 350 



The inquiry into the efficient cause of the chick is one of great difficulty . 355 



Of the efficient cause of animals, and its conditions 360 



Of the order of generation ; and, first, of the primary genital particle . 372 



Of the blood as prime element in the body 379 



Of the inferences deducible from the course of the umbilical vessel in 



the egg 392 



