E. I. IVANOFF -251 



questionnaire are of a very uniform character and confirm all the con- 

 clusions arrived at in the preliminary experimental work. Artificial 

 insemination during the above short period succeeded in gaining the 

 confidence of the ])opulation. In some cases the number of horses brought 

 to the pairing station during one pairing season ran into hundreds. It 

 has been ascertained that the number of mares fertilized during the 

 pairing season by one stallion can average 300 and over when the method 

 of artificial insemination is used. Sometimes the data of the question- 

 naire sup])ly indications that the young born were of a superior type, or 

 in any case perfectly sound. 



Only one case of deformity is recorded out of over 2000 foals born, 

 which proijortion is quite normal. 



As regards the proportion of positive results, the figures, as one could 

 expect from the foregoing, are by no means uniform. The percentage of 

 conceptions varies between 4 and 907 and averages about 40. 



For 1909 the proportion of conceptions was 40 % 



„ 1910 „ „ „ 40-3 % 



1911 35-5°, 



• 



1912 41-4 "/ 



1913 4''-3 °/ 



When we look into that disparity in the results of the work of difierent 

 people, we find that it was caused by those irregularities, which crept 

 into the work, as the data of the questionnaire clearly show. For 

 example, if we were to divide the material at our disposal into two 

 sections, one under the heading "Artificial insemination performed on 

 mares in period of 'heat,'" and the other "Artificial insemination per- 

 formed regardless of presence or absence of 'heat,'" we should find that 

 in the first group, where a number of other irregularities and deviations 

 from proper conditions of work remained and only that factor of "in- 

 semination without 'heat'" was excluded, the proportion of positive 

 results equalled 49 % , while in the second group, where that factor 

 remains, the percentage of positive results was 28. 



When we examine in both these groups the influence of the factor 

 of duration of the pairing season, we find that when 



The duration of pairing season is The % of conceptions 

 Less than one month for 1st group 38-6 



., 2nd „ 19 



Over one month ,, 1st „ 54 



„ 2nd „ 29 



