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THE AMERICAN NATURALIST [Vol; LIII 



curve for the year ending October 31 is of the bimodal 

 type.3 



One of these modes, appearing on the spring of the 

 year (in April), may be termed the vernal production 

 maximum. The second mode, falling in September, may 

 be called the autumnal production maximum. Of these 

 two maxima for the first laying year the vernal maximum 

 manifests the higher peak, in keeping with the heavy 

 April production which is the highest of the year. Be- 

 tween any two successive maxima lies a fundus whose 

 minimum is attained either in July or August, or in No- 

 vember of each year. The late summer depression may 

 be termed the cestivcd production minimum, and the No- 

 vember depression, the autumnal production minimum. 

 In the month of December of the second laying year it 

 will be noted that the curve rises slightly. This repre- 

 sents the increased production of the "winter cycle" or, 

 as it may be called, the hibernal production maximum. 

 Between this and the vernal production maximum of tlie 

 second laying year is another depression in the curve, 

 following llio ])oriod of winter production and indicating 

 111,- irilu n,nl ,nnd,ni;nn minimum. This is followed in 

 liini 1»\ llic xci iial iii;i.\iiinim of the second year. 



TJic pi'csciicc ot* llicsc two maxima in the curve of pro- 

 duction I'oi- llir (ii'si l;i\ ing year indicates that at least 

 twice dni-iiiu' this ynw (closlii-- October 31), once in tlic 

 spring Mild once in tli*' ;mniriiii, tin; egg production of ;i 

 hen rises from its lower limits and expresses itself by 

 laying a larger number of eggs than at any other season. 

 These periods of increased production represent the 

 spring and the autumn cycles respectively. There exists 

 aNo thr wint.T cych' which is usnaily manifested with 



