232 THE AMERICAN NATURALIST [Vol.LII 



early start makes a comparatively high record. Finally 

 there is the type of bird shown by No. 4797, Fig. 11, that 

 matures early, lays steadily and does not go broody but 

 lays at a comparatively slow rate. Such birds may make 

 high records, but they never make the highest ones. 



Mediocre producers (under thirty eggs) may result 

 from any one of the various types previously described 

 for high producers through the failure of one or more fac- 

 tors. Thus, delayed maturity will cause a bird to fali 

 below the dividing line at 30 eggs to a degree that will 

 vary inversely with the age at first egg, due allowances 

 being made for the date at which the individual was 

 hatched (Fig. 4). Or a bird may fall below the required 

 number of eggs through a slow rate of production (No. 

 5080, Fig. 11, or Nos. 224 or 284, Fig. 12). The former 

 type of bird (Fig. 4) would seem to be a late maturing 

 high, since it is clear that its record results directly from 

 the variability in time of first egg. Hence this type of 

 mediocre producer is to be regarded as an artificial class 

 rather than a real class as in the case of the birds typified 

 by No. 5080. 



Zero producers, by definition, are birds that do not 

 lay until after March 1, and need no further discussion, 

 except to note that some of them clearly result from the 

 combined effects of date of hatch and age at first egg 

 rather than from an inherent inability to lay during the 

 winter (i. e., from a lack of the winter cycle). 



There are, then, numerous types of records resulting 

 from the interaction of the various components described 

 in the earlier part of the paper. Although the records 

 described are winter records, the observations apply 

 equally to annual egg production. High egg production 

 results only from a combination of the right set of fac- 

 tors. If any one of several of these factors fail, egg pro- 

 duction is lowered. 



(To be concluded.) 



