10S R.J.ANDERSON [august 1899 



mechanical and due to the nature of the roosts. These breeders look 

 upon the weakness naturally associated with the preparation of pure 

 breeds of fowls as a predisposing cause. 



Light pure bred fowls have been often observed to have crooked 

 keels, whilst heavy breeds, if the birds are not allowed to roost early, 

 have not the deformity. The following is a note from a breeder : — " A 

 ' black Norfolk turkey ' with a crooked breast was mated with a 

 straight-breasted hen. All the chicks got the same treatment, the 

 roosts were low and flat, and covered with straw until the birds were 

 able to fly." Notwithstanding these precautions five cock birds out of 

 the sixteen birds which formed the flock had crooked breast keels. 

 Water-fowl have sometimes crooked breasts ; the deformity here is not 

 due to roosting. The most crooked sternum in my possession belonged 

 to a Brahma. The keel, where the bend is greatest, is nearly hori- 

 zontal There are marks of pressure on the keel edge in some cases. 

 A distinct broadening of the edge of the keel is perceptible, in two bent 

 to the right, and in four bent to the left. An indentation occurs in 

 front of the middle of the two keels bent to the left. Two keels have 

 marks of having been broken and reunited. The wry tail has been 

 attributed to the bird roosting too near the wall, and to the tendency 

 to form a compensating bend in consequence of the breast being bent 

 to the opposite side. The fanciers who believe that it is due to in- 

 herent weakness because of the breeds being run out, seek to correct 

 the tendency by the introduction of new stock. The wry-tailed birds 

 are discarded. The evidence goes to prove that — 



(1) Malformation is commonest in pure breeds. 



(2) In-and-in breeding tends to develop wry tails and crooked keels. 



(3) The distortion is frequently transmitted from parent to off- 



spring. 



(4) Roosting on round or sharp roosts tends to promote the 



distortion. 



Summary. 



(1) The shape of a body may be due to forces within or pressure 



without, or both. 



(2) The same kinds of symmetry are to be observed in inorganic 



and organic forms. 



(3) The forces at work inside organisms are " vital " and physical. 



The resultant figures are the expression of the work of two 

 or more sets of agents. 



(4) Asymmetry may be due to causes internal or external, or both. 



I have to thank Dr. G. J. Allman for the opportunity of con- 

 sulting his father's manuscript. 



Queen's College, 

 Galway. 



