No. 590] SHORTER ARTICLES AND DISCUSSION 



127 



lamb was born having a short length of back and short bandy- 

 legs. Seeing an advantage in such an animal owing to its in- 

 ability to jump fences, it was bred to the flock, the original ram 

 being killed. The first year thereafter two lambs had the pecu- 

 liarities of their father, and in following years a number more 

 Ancon lambs were produced. The latter when bred together 

 always, with one questionable exception, produced Ancons. 



Hence the character was evidently a recessive, having orig- 

 inated from the normal through a negative variation or mutation, 

 presumably in one germ cell. This being the case, the variation 

 must have been carried in a latent or recessive condition for a 

 certain number of generations until inbreeding brought it out in 

 a homozygous form. The original ram which was killed must 

 have been heterozygous for this character, also one at least of the 

 ewes and probably more; for one such heterozygous ewe was 

 necessary to produce the original Ancon ram, and the two Ancons 

 which appeared next year in the back-cross not improbably came 

 from different mothers. It is therefore impossible to say just how 

 long this condition may have been handed on in a "latent" con- 

 dition before inbreeding brought it out. 



With few exceptions, the Ancons showed alternative inherit- 

 ance when crossed with normal sheep, and (1. c, p. 90). 



Frequent instances have happened where common ewes have had 

 twins by Ancon rams, when one exhibited the complete marks of fea- 

 tures of the ewe; the other of the ram. 



Incidentally this shows that such twins came from separate ova. 



In a flock the Ancon sheep tended to keep together and separate 

 from the normal members of the flock. The breed seems to have 

 attained some popularity, but their flabby subscapular muscles, 

 infirm construction, loose joints, crooked forelegs and awkward 

 gait, while preventing them from jumping fences made them 

 difficult to drive to market. Butchers also found the carcasses 

 smaller and less saleable, so that they were soon supplanted after 

 the introduction of the Merino. They were already scarce in 1813 

 and afterwards became extinct. 



Huxley remarks regarding this case: 



Varieties then arise we know not why; and it is more than probable 

 that the majority of varieties have arisen in this " spontaneous " man- 

 ner, though we are, of course, far from denying that they may be traced, 

 in some cases, to distinct external influences. ... But however they 

 may have arisen, what especially interests us at present is, to remark 



