EXPERIMENTS WITH ALCOHOL 153 



From the data given in this table it is apparent that this 

 stock cannot, on the average, be considered to be closely inbred. 

 The mean coefficients, except in the case of Zi, are very decid- 

 edly smaller than the coefficients for single first cousin mating. 

 In all the matings except 1536, 1785, and 1788 the value of Zx 

 is zero. Two of these are half brother and sister matings and 

 the third is a full brother X sister mating. Omitting these 

 three matings we get for mean values: Zi = 0, Z^ = 13.63, 

 Zg = 26.14. 



That the mean coefficients of inbreeding for the foundation 

 stock in these experiments should be higher than those for a 

 random sample of the general population of Jersey cows (data 

 from Pearl and Patterson, 25, p. 60) is in no way remarkable 

 when it is recalled that the Barred Plymouth Rock flock of the 

 Maine Station has been line-bred for a long time. It is equally 

 clear that the degree of inbreeding exhibited by the present 

 poultry stock is well below the degree (if there be any such) 

 which, 'per se, causes a weakness and lack of constitutional 

 vigor. This is evident from many considerations. Data which 

 will be presented later on in this paper demonstrate it. In 

 this connection it is of interest to examine a little more closely 

 the performance of the individuals from the most closely in- 

 bred mating of table 3. Mating 1785, which was of brother X 

 sister, contributed two individuals, 1482 and 1741, to the mat- 

 ing list of the alcohol experiments. It will be shown in table 1 

 of paper No. Ill in this series that 1482, the ethyl treated sister, 

 produced eggs giving a 75.0 per cent hatch on the basis of all 

 eggs set, and 81.8 per cent on the basis of fertile eggs. No. 

 1741, the untreated sister, did nearly as well. Of all of her 

 eggs set 70.0 per cent hatched; of her fertile eggs 77.8 per cent 

 hatched. In neither of these records can one find any evidence 

 of constitutional weakness, induced by inbreeding or in any 

 other way. 



We may summarize the results of our examination of inbreed- 

 ing in the foundation stock used in these experiments by saying 

 that while it is a sample from a line-bred population and is 

 therefore, to some degree, inbred, the amount or intensitv of 



