ABSTRACTS. 303 



3. Since the laying year 1907-08 there has been a steady 

 increase in mean winter production for the whole flock, ex- 

 cept for the years 1910-11 and 1914-15. In the former year 

 the decline in the mean is slight, and is probably due to un- 

 favorable environmental influences. In 1914-15 the decline is 

 certainly due to such causes. 



4. That selection on a progeny test basis was effective is 

 demonstrated not only by the general flock averages, but also by 

 the fact that it was possible to propagate separately high and 

 low producing strains. The high producing strains differed 

 widely from the low producing in mean winter production. Tak- 

 ing the average for seven years in the case of the high, and 

 four years in the case of the low, it appears that the mean win- 

 ter production of the high producing strains was approximately 

 two and a half times that of the low producing strains. At the 

 end of the laying year 1911-12 the low producing lines were 

 dropped. In the next year (breeding season of 1913) no birds 

 were bred which were known to belong to segregating lines. 

 Of course some were included which proved afterwards to 

 have been segregating, but this fact could not, in any such 

 case, have been told in advance from the records in hand. 



A SYSTEM OF RECORDING TYPES OF MATING IN 

 EXPERIMENTAL BREEDING OPERATIONS.* 



This paper is of interest only to the experimentalist. It 

 describes a uniform and comprehensive method of describing 

 numerically the different forms of pedigrees which arise in 

 Mendelian work. 



MEASUREMENT OF THE WINTER CYCLE IN THE 

 EGG PRODUCTION OF DOMESTIC FOWL.* t 



In this paper quantitative evidence is presented which shows, 

 with flocks of poultry having average hatching dates falling 

 somewhere within the month of April, that — 



*This is an abstract of a paper by Raymond Pearl, having the same 

 title and published in Science N. S. Vol. XLII, pp. 383-386, 1915. 



*tThis is an abstract of a paper by Raymond Pearl, having the same 

 title and published in Journal of Agricultural Research, Vol. V, pp. 

 429-437. 1915. 



