302 



GEORGE W. BARTELMEZ 



135 degrees. A curve, (diagram IV) based on all the eggs I 

 studied, viz., 299, taken from eighty-two different birds, shows 

 that these extremes are rare. Four modes appear in the curve, 

 at 50, 70, 80 and 90 degrees. This suggests the most inter- 

 esting condition that has appeared from this study of axis 

 angles; namely, that the relation between embryonic, and long 

 axes is far more constant for the eggs of an individual than for 

 eggs obtained from different birds — a maximum variation of 50 

 against 127 degrees. Table 2 shows that most of the eggs laid 

 by a given bird have almost identical relations, when one re- 

 members that five degrees is a very slight variation under such 

 conditions as these : 



TABLE 2 



It appears that there is one grouping of the eggs of no. 3, about 

 100 and another about 125 degrees. The fact that it is so excep- 

 tional to find a pigeon's egg in which the axial angle is greater 

 than 90 degrees makes the case all the more striking. The 

 record of no. 2 shows that her eggs occasionally had the axis 

 angle greater than 90 degrees; among the eggs of the other 

 eighty birds studied, only twelve of the remaining 287 had angles 

 of 90 degrees or more. The variation in no. 4 is more typical. 

 In the curve, (diagram IV) 66 eggs obtained from the two birds 

 whose axis angles were constantly greater than 90 degrees, are 

 omitted; the dotted line at the right shows the curve with these 

 eggs included. 



