324 GEORGE W. BARTELMEZ. 



itself. The evidences I found in ovarian and oviducal eggs were 

 enumerated in my 1912 paper and I hope soon to publish the 

 details of these observations. 



II. HISTORICAL REVIEW. 



A. The Principal Axis of the Egg. Aristotle devoted much 

 attention to the hen's egg and he speculated at length upon the 

 difference between the two ends of the shell. The Aristotelian 

 doctrine, which is to be found elaborated even in some relatively 

 recent papers may be stated as follows: The ovum drops into 

 the oviduct as an apple from the tree; the ovarian pedicle of the 

 oocyte becomes the pointed end chalaza which passes last down 

 the duct and the theca folliculi becomes the shell membrane. 

 The pointed end is the "principium ovi, where the first rudiments 

 of the egg are fashioned." This philosophy was based chiefly 

 upon two observations of Aristotle's: The ovarian stalk or pedicle 

 is characteristically long in the hen's oocyte and the blunt end 

 of the egg is laid first. Harvey's account of the early develop- 

 ment is the first clear and accurate one for he understood the 

 nature and destiny of the "cicatricula." He was able therefore 

 to correct the error concerning the "principium ovi" as well as 

 many others which his predecessors had made. However much 

 he chuckled over the blunders of others, Harvey was always 

 at some pains to explain or extenuate the errors of the Great 

 Master. His discussion of Aristotle's statement that the shell 

 does not harden until it reaches the outer air is well worth 

 reading (1651, Exercitatio XL). 



B. The Air Space. Harvey was the first to observe the air 

 space carefully; he found it at or near the blunt end of the hen's 

 egg and he cites a common belief that if it is at the center of the 

 blunt pole a male will be produced. He describes it as very 

 small at laying, growing larger as incubation advances, v. Baer 

 (1828) was the first to note that it is not present at all in oviducal 

 eggs nor at the moment of laying. Coste (1847, p. 306) is the 

 only one apparently, who has seriously considered the problem 

 of the air space. He confirmed v. Baer's observations and 

 showed that as the egg cools after laying atmospheric air enters 

 through the shell and forms the space between the two layers 



