156 Essay on the Interpretation of Milk Records. 



deviation/ nor on system of grouping, as is the modal coefficient - 

 (percentage of total variates as to the mode). 



Take first the case of normal lactation periods. Of 2,665 

 records examined for this point 1,233 were found to have been 

 those of cows in milk from thirtj'-five to forty-five weeks, and 

 successfully put to the bull not later than the sixteenth week 

 after calving. 



The lactation totals, averages fifth to twelfth week, maxima, 

 and " revised maxima " of these 1,233 " normal cows " gave 

 the four following frequency curves : — 



Fig. 1. — Frequency Cuevks : 1,233 Normal Lactations. 



Lactation Totals - 

 Averages 

 Maxima 

 Revised Maxiraa- 



TotalB (gallons) inO 200 300 400 500 600 700 800 800 1000 1100 IJOO 1300 1400 1500 



Avenges (quarts) 2b 4-5 65 S'S lO'S 12 5 14-6 Ifl'S 185 205 22-5 24-5 26-5 28-5 30-5 



Maxima „ \ 



R.M. „ f 



4-5 6-5 85 10-5 125 14-5 165 185 20-5 22 5 245 28o 2S-5 SOS 325 



Totals in gallons ; remainder in quarts. 



1 Karl Pearson : " On the dissection of asymmetrical frequency curves," 

 Phil. Trans. Roy. tSoc, clxxxv., 1894, page 71. 



' E. Davenport : Prineijdes of Breeding, page 422. 



