356 GEORGE W. BARTELMEZ. 



(e) In about one half the clutches studied the angles of the 

 first and second eggs agreed closely. This is a matter of great 

 practical importance in the study of ovarian and oviducal eggs. 



(/) Inversions are due either to the reversal of the long axis 

 of the ovum at about the time of ovulation or they may be due 

 to the reversal of the polarity of the oocyte early in oogenesis. 



(g) The long axis could be identified in 96 per cent, of the 

 eggs studied, the chalazal axis in 97 per cent. The two coincided 

 in 98 per cent, of normal eggs. 



(A) The chalazae were found abnormal in only 3 per cent, of 

 cases but more or less atypical in 20 per cent, of cases. 



(i) In 58 per cent, of the eggs the cloacal (i. e., pointed end) 

 chalaza was strikingly larger than the other. 



I am indebted to the Librarians of the Surgeon General's 

 library and of the Harvard Library for the loan of several of the 

 older works mentioned and to Miss E. Dickenson of the Univer- 

 sity of Chicago Library for help in tracing many of the earlier 

 references. 



BIBLIOGRAPHY. 



The titles marked with an * do not appear or are inaccurately cited in the bibliog- 

 raphy of Keibel und Abraham's Normentafel or the corresponding work of Grosser 

 und Tandler. 



Aldrovanus, U. 



1646 Opera Omnia Lib. I-III. Bononiae, 1646. 

 Aristotle (324-322 B.C.) 



De generatione animalium. Translated by A. Platt. Oxford, 1910. 

 v. Baer, C. E. 



i828-'88 Ueber die Entwickelungsgeschichte der Thiere Beobachtung und 

 Reflexion. I. Theil, 1828; II. Theil, no. i, 1837; II. Theil, no. 2, 1888 

 (Ed. L. Stieda). Leipzig. 

 Barry, M. 



1838 Researches in embryology, ist Series. Philosophical Transactions, p. 



301. London. 

 Balfour, F. M. 



See Foster & Balfour. 

 Bartelmez, G. W. 



1912 The Bilaterality of the Pigeon's Egg. Jour. Morph., Vol. 23, p. 269. 

 Berthold, A. A. 



1829 Ueber die Bildung und den Nutzen der Hagel (Chalazae) im Vogeley. 



Isis, 1829, p. 404. 

 Blanc, L. 



Note sur I'influence de la lumiere sur 1'orientation de 1'embryon dans 1'oeuf 

 de poule. Compt. Rend. Soc. Biol., T. 44, p. 774. 



