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Fertility in Scottish Sheep. 



By Francis H. A. Marshall, M.A. (Cantab.), D.Sc. (Edin.), Carnegie 

 Fellow, University of Edinburgh. 



(Communicated by Professor E. A. Schafer, F.R.S. Eeceived August 10, 1905.) 



My attention was first directed to the subject of fertility by Mr. Walter 

 Heape, to whom I am much indebted. 



Experiments have been described in agricultural publications on the effects 

 of different methods of feeding and general treatment upon wool or meat 

 production ; but excepting, so far as I am aware, for Mr. Heape's report on 

 " Abortion, Barrenness, and Fertility " in sheep in the South of England for 

 the year 1896 to 1897,* no systematic attempt has been made to deal with 

 the factors which influence fertility either in the sheep or in other animals. 

 Numerous experiments, however, are annually conducted by flock-masters 

 for a practical object, and it has been thought desirable to put the results of 

 some of these on record with a view to making comparisons, and in the 

 hope eventually of reaching definite conclusions upon this subject. 



That differences in food and environment exercise an influence over 

 fertility in the sheep as in other animals has long ago been recognised,f 

 and recently attention has been called to the wide range of variability 

 in the sheep's sexual capacity, this animal showing a complete gradation 

 between the monoestrous condition and the most extreme degree of 

 polyoestrum.J 



As a preliminary step in an investigation on fertility in sheep, it was decided 

 to issue a schedule of queries addressed to various flock-masters chiefly in 

 the East of Scotland. The present communication consists of a condensed 

 account of some of the information contained in their replies.§ 



The preparation and issue of the schedule was undertaken by the Highland 

 and Agricultural Society of Scotland, under whose auspices the work is being- 

 carried on. I am under no light obligation to the members of this society 

 for their co-operation, as well as to all those gentlemen who have supplied 



* " Abortion, Barrenness, and Fertility in Sheep," ' Journ. Boy. Agric. Soc.,' vol. 10, 

 1899. " Note on the Fertility of Different Breeds of Sheep," ' Boy. Soc. Proc., : vol. 64, 

 1899. 



t Darwin, " Animals and Plants," Popular Edition, London, 1905. 



X Marshall, " The (Estrous Cycle and the Formation of the Corpus Luteum in the 

 Sheep," 'Phil. Trans.,' B, vol. 196, 1903. 



§ It is hoped that a full report may be issued next year in the ' Transactions ' of the 

 Highland Society. 



