330 GEORGE W. BARTELMEZ. 



he thought after ovulation, it must nevertheless be remembered 

 that practically every objective drawing of an entire ovarian 

 oocyte shows a well-defined long axis. Pfeil describing a mature 

 oocyte of the hen in 1823 says "... vitello in sacco scilicet 

 rotundo, globoso" and Purkinje in 1825 (p. i) mentioned the 

 'somewhat oblong' shape of the young oocytes. He saw also 

 the elongate shape of the mature oocyte but thought it was due 

 to the pressure of the oviduct (see pp. 9 and 20, 1830 edition). 



Allen Thompson (1839) and Balfour (1874) completely con- 

 firmed von Baer's description while several workers have de- 

 scribed the long axis in ovarian oocytes of the hen without recog- 

 nizing its significance. The following may be mentioned: His 

 (1868), Nathusius (1868), Sonnenbrodt (1908) and Riddle (1911). 



The observations of Haswell '1887) are particularly significant 

 in this connection. With v. Baer's description in mind he studied 

 the egg of the emu, found the yolk measuring 70 X 75 mm., 

 the long axis coinciding with the principal axis and the relations 

 of the embryo as they are in the hen. He found the yolk ovoid 

 rather than oval in shape, the more pointed end corresponding 

 to the pointed end of the shell. I have occasionally seen the 

 same condition in the pigeon's egg, but in this form attached no 

 particular significance to it, as in some such cases the more 

 pointed end was directed toward the blunt end of the shell. 



In the pigeon the yolk is more markedly elliptical than in the 

 hen and since it does not lose its shape through imbibition of 

 albumen during the first two days of incubation as the hen's egg 

 is apt to do, the long axis can hardly escape notice. It averages 

 ten per cent, longer than the other axes of the yolk (see p. 342). 

 It was a matter of no small gratification to find three years after 

 writing it that I had almost duplicated v. Baer's description 

 of the orientation of the hen's egg in my account of the pigeon's 

 egg (1912). In his day the problems of bilaterality had not yet 

 come to the fore and so he did not take the next logical step and 

 point out the significance of the fact that the embryonic axis is 

 definitely related to the ovarian long axis. 



In most pigeon's eggs we find the polar axis the shortest; 

 that is, in addition to being shorter than the long axis, it is 

 usually shorter than the axis perpendicular to these two which 

 I term the transverse axis (Bartelmez, 1912, p. 290 and p. 342 



