September 20, 1912] 



SCIENCE 



379 



It then became obvious that sheep, like 

 human beings, have only two nipples; and 

 that they are located, as in the case of the cow, 

 on the belly between the hind legs. 

 , It was also found at this examination in 

 1890 that some sheep have four nipples instead 

 of two. Two of these were in the usual place 

 and of the usual size; the extra pair lay in 

 front, upon the belly; and the nipples were 

 extremely small and undeveloped, more nearly 

 resembling pimples upon the skin than nip- 

 ples. They were embryonic in character and 

 yielded no milk. 



At once interesting questions began to 

 arise: Could we, by mating four-nippled ewes 

 with four-nippled rams, and by selecting from 

 their progeny for breeding purposes the lambs 

 in which the extra nipples were most fully 

 developed, gradually create a variety of sheep 

 that would have four nipples of equal size, all 

 yielding milk? 



If we could, by selection, create a four- 

 nippled variety of sheep, why not a six-nippled, 

 an eight-nippled, or a multi-nippled variety? 



It was also found in 1890 that the propor- 

 tion of sheep having four nipples was larger 

 among the twin-bearing than the single-bear- 

 ing ewes; and this at once raised the question 

 as to whether there was any correlation be- 

 tween the number of nipples and the number 

 of lambs at a birth. 



If the four-nippled variety should turn out 

 to be twin-bearing, as a rule, would the six- 

 nippled and eight-nippled varieties give us 

 triplets and quadruplets ; and would the multi- 

 nippled ewes have a litter at birth? 



Twins, etc., are usually smaller at birth than 

 single lambs, even after they have become 

 mature, probably because their mothers are 

 unable to supply sufficient milk for two or 

 more lambs when the ewes have only two func- 

 tional niammse. 



Would a sheep supply more milk from four 

 functional nipples than two; and if so, would 

 she be able to care for two lambs as easily as 

 one? 



A twin-bearing stock, able to rear twins suc- 

 cessfully, would undoubtedly be of great value 

 in a country like Nova Scotia, where the win- 



ters are long and the cost of sheep-breeding 

 correspondingly great. If the farmers could 

 raise two lambs instead of one for every ewe 

 wintered, sheep-breeding in Nova Scotia might 

 become a profitable industry of great impor- 

 tance. 



These considerations led to the sheep-breed- 

 ing experiments upon Beinn Bhreagh. I must 

 here express my indebtedness to Mr. J. G. 

 Davidson, Superintendent of Beinn Bhreagh 

 Nursery, who has, for the last ten years, had 

 charge of the experiments under my direction. 



A Four-nippled Variety of Sheep. — ^By pur- 

 suing the plan of selection outlined above, we 

 succeeded in producing upon Beinn Bhreagh, 

 in a very few years, a four-nippled variety of 

 sheep in which the ewes had, as a normal con- 

 dition, four nipples of nearly equal size, all 

 yielding milk. 



So few cases of reversion to the ordinary 

 two-nippled type appeared among the lambs 

 that I felt justified in bringing the matter to 

 the attention of the National Academy of 

 Sciences, at their meeting in Washington, 

 D. C, April 21, 1904.' At the same time I 

 presented to the National Academy of Sci- 

 ences, in pamphlet form, the " Sheep Cata- 

 logue of Beinn Bhreagh, Victoria County, 

 Nova Scotia, showing the origin of the Multi- 

 nippled Sheep of Beinn Bhreagh, and giving 

 all the descendants down to 1903." ' 



This four-nippled breed was not slowly 

 evolved by the persistent mating together of 

 sheep having extra nipples of embryonic char- 

 acter. It sprang suddenly into existence; 

 for it was soon discovered that it was possible 

 to pick up here and there, from the farmers 

 of Cape Breton Island, ewes with four func- 

 tional mammae already fully developed. These 

 were added to our flock and hastened the ac- 

 complishment of the result. 



In a few years after the experiments were 

 begun in 1890, we had so many four-nippled 

 sheep that we were able to cut down the flock 



' See Science, Vol. XIX., p. 767. 



' This pamphlet may be found in many public 

 libraries; the Library of Congress, Washington, 

 D. C, Boston Public Library, the Library of the 

 British Museum. 



