256 SOME RESl'LTS OF OSTRICH INVESTIGATIONS. 



the same time the two races have many distinctive characters 

 which are hereditary and therefore germinal. 



Crossing of the Northern and S(m;tiiern Ostriches. 



While the main object of the investigations is the practical 

 one of determining to what extent the plumage of the southern 

 bird can be improved by crossing with the northern bird, in the 

 course of the work many other questions have arisen which have 

 an interest to students of genetics generally. It has been j^ossible 

 to determine how the characters distinguishing the two species 

 behave in the hybrids or cross-bred birds. Those specially studied 

 comprise the dimensions, colour, the bald head patch, and details 

 connected with the egg. 



Dimensions. 



On account of its restless, nervous nature, and the difticulty 

 of fixing upon constant determinable ])oints, the live ostrich is 

 not a creature which lends itself to accurace bodily measurements. 

 In any troop it will be found that the members differ much among 

 themselves, and the same individual varies at different ages, and 

 according to its nutritive condition. Hence the northern and 

 southern birds and the crosses from them can be compared only 

 in general terms, as when seen side by side. The average North 

 African ostrich is a much taller bird than the South African, being 

 longer in the legs and neck. The head reaches to a height of 

 from eight to nine feet from the ground, whereas in the Cape bird 

 it extends only seven to eight feet. The feet, legs, and neck of 

 the Nigerian bird are also more robust. The general dimensions 

 of the body do not differ much in the two, the greater size of the 

 northern being mainly a result of the longer legs and neck. As 

 a chick and young bird, the body of the northern ostrich, however, 

 tends to narrow behind more than the southern, but later this 

 becomes a feature largely dependent upon the nutritive state. 

 The relative sizes admit of the two being easily picked out in a 

 mixed troop, the heads of the northern birds towering a foot or 

 so above those of the southern. 



The cross-breds at maturity stand higher than pure Cape 

 birds, but are not so high as the Nigerian. As chicks, the body 

 tends to narrow behind more than in Cape chicks, so that, with the 

 slightly longer legs and tapering body, they appear decidedly more 

 slender than Cape chicks of the same age. On the whole it can 

 be said that as regards size, especially length of limbs and neck, 

 the hybrids follow neither one parent nor the other, but are inter- 

 mediates between the two, though the statement is not one which 

 can be supported by actual measurements. 



The two chicks of the second cross-bred generation ( PI. 31; ) 

 already reared are now a year old, and as regards their general 

 size are strikingly like the South African grandparent, as con- 

 trasted with the North African, including the shorter, less robust 

 legs and neck. When mingling with first generation cross-breds 



