CH. XV] ON THE SHAPES OF EGGS, ETC. 653 



We need do no more than mention Aristotle's belief, doubtless 

 old in his time, that the more pointed egg produces the male 

 chicken, and the blunter egg the hen ; though this theory survived 

 into modern times* and perhaps still hngers on. Several natural- 

 ists, such as Giinther (1772) and Biihle (1818), have taken the 

 trouble to disprove it by experiment. A more modern and more 

 generally accepted explanation has been that the form of the egg 

 is in direct relation to that of the bird which has to be hatched 

 within — a view that would seem to have been first set forth by 

 Naumann and Biihle, in their great treatise on eggs f, and gCdopted 

 by Des MursJ and many other well-known writers. 



In a treatise by de Lafresnaye§, an elaborate comparison is 

 made between the skeleton and the egg of the various birds, to 

 shew, for instance, how those birds with a deep-keeled sternum 

 laid rounded eggs, which alone could accommodate the form of the 

 young. According to this view, that "Nature had foreseen||"' 

 the form adapted to and necessary for the growing embryo, it 

 was easy to correlate the owl with its spherical egg, the diver 

 \vith its elliptical one, and in like manner the round egg of the 

 tortoise and the elongated one of the crocodile with the shape of 

 the creatures which had afterwards to be hatched therein. A few 

 writers, such as Thienemann^, looked at the same facts the other 

 way, and asserted that the form of the egg was determined by 

 that of the bird by which it was laid, and in whose body it had 

 been conformed. 



In more recent times, other theories, based upon the principles 

 of Natural Selection, have been current and very generally accepted, 

 to account for these diversities of form. The pointed, conical 

 egg of the guillemot is generally supposed to be an adaptation, 



* Cf. Lapierre, in Buffon's Histoire Naturelle, ed. Sonnini, 1800. 



t Eier 4er Vogel Deutschlands, 1818-28 (cit. des Murs, p. 36). 



t Traite d'Oologie, 1860, 



§ Lafresnaye, F. de, Comparaison des cBufs des Oiseaux avec leurs squelettes, 

 comme seul moven de reconnaitre la cause de leurs differentes formes, Bev. ZooL, 

 1845, pp. lSO-187, 239-244. 



II a. Des Murs, p. 67: "EUe devait encore penser au moment ou ce germe 

 aurait besoin de I'espace necessaire a son accroissement, a, ce moment ou...il devra 

 remplir exactement I'intervalle circonscrit par sa fragile prison, etc." 



^ Thienemann, F. A. L., Syst. Darstellung der Fortpflanzung der Vogel Europas, 

 Leipzig, 1825-38. 



