342 GEORGE W. BARTELMEZ. 



All of the twelve eggs that were incubated to hatching produced 

 normal young. 



The only irregularity during almost two years was the laying 

 of one clutch with a single egg. This is usually due to the failure 

 of the first or second egg to enter the oviduct at ovulation or to 

 its escape soon after. More rarely only a single ovum matures 

 at a time. 



The range of variability (Fig. 3, j) is striking as it ranges from 

 90 to 130 degrees, whereas it is uncommon jn the pigeon to find 

 the angle greater than 90 degrees. The actual variability is 

 small, and while this might be attributed to the small number of 

 cases I am inclined to think the small number of extreme variants 

 is to be correllated with the exceptionally well marked long axis 

 and the uniformly normal chalazae. Clutch 395 may serve as 

 an example of the size relations of the axes of the ovum : 



First egg (primitive streak embryo) 21.8 mm. (long axis), 19.5 mm. (transverse 



axis), 18.0 mm. (polar axis). 

 Second egg (10 somites) 20.7 mm. (long axis), 17.6 mm. (transverse axis), 18.0 



mm. (polar axis). 



We have in this case then a clue to the amount of variability 

 which we must expect in eggs of a single bird where the ovum is 

 normal and there are no irregularities in the functioning of the 

 oviduct. That is to say, in this case the variations due to im- 

 perfect orientation in the oviduct and errors of observation due 

 to abnormal chalazae have been practically eliminated. 



Pigeon No. 4. This bird and her mate had recently paired 

 when first observed. The first egg was laid January 4, 1910. 

 After sixteen clutches had been laid during thirteen months the 

 male was killed by a Diener. Two months later no. 4 mated 

 again and continued laying for the 'next three years. A similar 

 experiment was made purposely with no. 6 in order to see whether 

 any difference could be observed between the eggs laid during 

 the two matings. During the next two years no. 4 laid 29 

 clutches; and six during her last year; none of these last could 

 have hatched as the table shows. She was killed March 21, 

 1914, when an abnormal egg was found in the "uterus," although 

 ovary and oviduct appeared normal. The abnormality in the 

 last year may have been due to the sperm although the male 

 was apparantly normal and younger than his mate. 



