76 EXPEEIMENT STATION EECOKD. 



molt. If tlie juvenile feather Is removed from the follicle the next feather 

 produced by that follicle will be the secondai-y sexual feather, and not a feather 

 of the juvenile tyi^e. After that all further regenerations are of the sexually 

 differentiated feather." 



The measurement of changes in the rate of fecundity of the individual 

 fowl, R. Pearl (Science, n. ser., 40 (WW, No. 1028, pp. 383, 384; a&S- in Maine 

 Sta. Bui. 234 (1914), pp. 283, 284).— This is a preliminary paper calling atten- 

 tion to a method of measuring and representing graphically changes in the 

 intensity of ovarian activity, as Indicated by rate of ovulation in the domestic 

 fowl. 



It is said that " by a simple statistical expedient it is possible to represent 

 the changes in rate of fecundity in an individual bird as a continuous curve, 

 of which the ordinates represent the rates of egg production on a percentage 

 scale (0 to 100) at the time intervals plotted as abscisste. This is done by 

 taking, as the rate of fecundity for any given day Pn, the percentage which 

 the actual number of eggs laid by the bird during the 21 days, of which Pn 

 is the central day, is of 21. Put as a formula, if — 



RPn=rate of fecundity (or ovarian activity as indicated by ovulation) on 



the day Pn, 

 l=i\n egg produced, and 

 S denotes summation between the indicated limits, we have — 





" The rates so calculated for each successive day may be plotted as a 

 curve. . . . 



"Applying this method to records of one, two, and three-year-old hens many 

 interesting and novel points regarding ovarian activity, as expressed in ovula- 

 tion, may be made out. The long-period secular cycles of production appear 

 much more clearly and precisely than in flock mass statistics. The steady 

 diminution in maximum rate of fecundity per unit of time after the first spring 

 cycle in the bird's life is very strikingly shown in the great majority of cases. 



" This method of measuring fecundity opens the way to the attacking in the 

 individual of a number of problems which hitherto have only been amenable 

 to indirect, statistical treatment. Such, for example, are the questions of 

 relation of size of egg to rate of fecundity, the realtiou between fertility (in 

 the fowl readily measured by hatching quality of eggs) and fecundity.*' 



Poultry department, V. R. McBride (Washington Sta., West. Wash. 8ta. 

 Mo. Bui, 2 (1915), No. 10, pp. 26-30, fig. i).— From records kept of the sub- 

 station flock, it is estimated that the average cost of feed for a laying hen 

 is $1.50 per hen per year, for the general-purpose breeds, such as Orpingtons, 

 Plymouth Rocks, and Langshans. The cost for Leghorns and Anconas has been 

 $1.35 each. The average cost of producing eggs has been IG cts. per dozen. 



In incubating and brooding trials, out of 3,000 eggs incubated 2,300 chicks 

 were hatched. The loss of chicks during the brooding period was 8 per cent. 

 It was found that chicks hatched from eggs weighing from 24 to 27 oz. per 

 dozen were more vigorous and grew more rapidly than those hatched from 

 abnormally large or very small eggs. The small eggs were about equal to 

 the larger ones in fertility, but the chicks hatched from these were lacking 

 in vitalitj'. The abnormally large eggs, weighing moi'b than 27 oz. per dozen, 

 were low in fertility and did not hatch well. 



