SECT. 3] AND EIGHTEENTH CENTURIES 141 



that nothing is given to the egg by the hen except heat is beginning 

 now to be in doubt, if the results of Chattock are correct. 



In the description of the development of the embryo in the hen's 

 egg, which remains to this day one of the most accurate, Harvey 

 says with regard to the spot on the yolk, which had, of course, been 

 seen and mentioned by many previous observers, "And yet I con- 

 ceive that no man hitherto hath acknowledged that this Cicatricula 

 was to be found in every egge nor that it was the first Principle of 

 the Egge". His description of the beginning of the heart, that 

 "capering bloody point" or "punctum saliens'\ is too famous to 

 need more than a reference. He thought that the amniotic liquid 

 was of "mighty use", "For while the embryos swim there, they are 

 guarded and skreened from all concussion, contusion, and other out- 

 ward injuries, and are also nourished by it". 



Thus he made no advance on the opinion which had for long been 

 held, namely, that the amniotic liquid or colliquamentum served 

 for sustenance. "I believe", he says, "that this colliquamentum or 

 water wherein the foetus swims doth serve for his sustenance and 

 that the thinner and purer part of it, being imbibed by the umbilicall 

 vessels, does constitute and supply the primo-genital parts, and the 

 rest, like Milk, being by suction conveyed into the stomack and there 

 concocted or chylified, and afterwards attracted by the orifices of 

 the Meseraick Veins doth nourish and enlarge the tender embryo." 

 His arguments for this are, ( i ) that swallowing movements take place, 

 and (2) that the gut of the chicken is "stuft" with excrement which 

 could hardly arise from any other source. He was thus led to divide 

 the amniotic liquid into two quite imaginary constituents, a purer 

 and "sincerer" part, which could be absorbed straight into the blood 

 without chylification, and a creamless milky part which could not 

 be treated so simply. 



"About the fourth day", says Harvey, "the egg beginneth to step 

 from the life of a plant to that of an animall." "From that to the 

 tenth it enjoys a sensitive and moving soul as Animals do, and after 

 that, it is compleated by degrees and being adorned with Plumes, 

 Bill, Clawes and other furniture, it hastens to get out." These and 

 other passages which deal with the forerunner of the theory of re- 

 capitulation are interesting, but we have already met essentially the 

 same idea in Aristotle. Harvey contributed nothing new to it. The 

 first point on which he went definitely wrong was the statement that 



