MAINE AGRICULTURAL EXPERIMENT STATION. I914. 5 



far removed from what is ordinarily thought of as agricultural 

 science. At first thought one would hardly suppose that the 

 application of pure mathematics would be necessary to make a 

 reasonable prediction of the probability that a cow which gave 

 a certain amount of milk at her first lactation as a heifer would 

 be a profitable or an unprofitable cow to keep to maturity. Yet, 

 as a matter of fact, the only scientific way by which to solve 

 this important problem is by the application of pure mathematics, 

 and it is this which has been done in the department of biology 

 at this Experiment Station. When the tables spoken of above 

 are completed and published in bulletin form it will be possible 

 for any farmer who keeps a record of the milk production of 

 his- heifers at their first lactation to predict, with an average 

 error of rather less than 2 per cent, what the production of 

 the same cow will be when she is seven years old. Further- 

 more it will be possible for a dairyman to give each one of his 

 cows an absolute rating in comparison with advanced registry' 

 animals of the same breed at any given age. If he will keep 

 a milk record, he can with the help of these tables say whether 

 or not a particular cow is better or worse, and by what propor- 

 tion, than the average of advanced registry cows of the same 

 age. 



DOUBLE-YOLKED EgGS. 



Since everyone has seen quite a number of double-yolked 

 eggs it is quite naturally and rightly concluded that they are not 

 unusual. However, we do not usually consider how many 

 single yolked eggs we see to every one that is double-yolked. 

 The Station flock produces 531 single yolked eggs to every 

 double-yolked egg. That is, only two-tenths of one per cent of 

 the eggs are double-yolked. The ratio of double to single 

 yolked eggs is less than twice as high as the ratio of twin to 

 single births in the human family. 



Recent study at this Station shows that all birds are not 

 equally likely to lay double-yolked eggs. In fact the great ma- 

 jority of birds never lay anything but single yolked eggs. There 

 are, however, birds which possess a tendency to lay double- 

 yolked eggs. Such an individual may produce several such 

 eggs. It has been further found that a bird which possesses 

 the tendency to lay double-yolked eggs is not equally likely to 

 produce them at any age. She is most likely to produce them 



