192-2.] 



The Sex of Eggs. 



Lienhart that the eggs from which male birds are developed 

 might also he heavier than those producing females. 



Experiments which he then made did appear to show that by 

 selecting for incubating eggs heavier than the average a larger 

 proportion than usual of male birds was produced. This was only 

 the case, however, when eggs of a single pure breed were used, 

 and it appeared that the result would be more certain if eggs 

 were used from fowls all of the same age and at the height of the 

 laying season. 



Further experiments at the Experimental Station of Ccligny 

 (France) have given the following results* : — 



Sitting of 15 eggs, medium weight, rather light, 8 hens, 4 cocks. 

 „ 15 „ „ „ „ heavy, 4 „ 7 „ 



„ „ 15 „ all heavy ... ... ... 4 „ 9 „ 



„ „ 15 „ light weight (below average) 9 „ 3 

 „ „ 15 „ (from 5 hens) lightest weight 11 2 

 Other experiments gave negative results and M. Lienhart found! 

 that these were always obtained with breeds of mixed on gin, 

 such as Faverolles, Mantes, Coucous de Malines, etc. With 

 Leghorn, Minorca and Bresse eggs, a large proportion of males 

 with heavy eggs, and a large proportion of females with light 

 eggs, were always obtained. 



In reality, the progenitors of the Faverolles had very dift>n nt 

 weight averages of eggs: — Houdan 1.94 oz., Brahma 1.87 oz , 

 Dorking 2.19 oz. It follows that certain families of Faverolles 

 have eggs approaching Houdan eggs, others Brahma eggs, and 

 others again Dorking eggs. If then, light Faverolles eggs 

 (average weight 2.12 oz.) are selected to obtain females, one 

 may include in the sitting heavy eggs of the Houdan type or 

 Brahma type and consequently obtain males. With eggs from 

 a single Faverolles hen, however, of which the eggs were of a 

 constant average weight, M. Lienhart obtained a majority of 

 males with the heavier weights and vice versa. 



These results are sufficient to encourage further investigation 

 into the possibility of making, under practical conditions, such a 

 selection of eggs for sitting that a large proportion of the sex 

 desired may be obtained. 



****** 



Journal cl Agriculture Pratique) 25th Feb., 1922. 



t Iiulletin de la Socicte de Biolof/ie, No. 3('>, 10th Dec., 1 4 .'21 . 



