288 MAINE AGRICULTURAI, EXPERIMENT STATION. I912. 



tions will not always, or even often be met. Further, as has 

 been especially emphasized by Herrick ( 18, 19, and other pa- 

 pers), egg laying in wild birds is simply one phase of a cyclical 

 process. If the cycle is not disturbed in any way the egg pro- 

 duction is simply the minimum required for the perpetuation of 

 the race. If, however, the cycle is disturbed, as for example, 

 by the eggs being removed from the nest as fast as they are laid, 

 a very considerable increase in the total number of- eggs pro- 

 duced will result. This, of course, is what happens under do- 

 mestication. What an effect in increasing the actual expressed 

 fecundity of a wild bird the simple removal of eggs as fast as 

 they are laid may have, may be illustrated by three cases from 

 the literature. Austin ( i ) shows that whereas the wild Mallard 

 duck in a state of nature lays only 12 to 18 eggs in the year, 

 it will lay from 80 to 100 if they are removed as fast as laid 

 and the bird is kept confined in a pen at night. Hanke (16) 

 by regularly removing the eggs got 48 in succession from a 

 common wryneck (Inyx torquilla^). Wenzer(53) in the same 

 way brought a house sparrow's productivity up to 51 eggs. 



With the domesticated Gallus the 'normal ovulation' factor 

 may be taken as inducing a production of anything up to from 

 forty to eighty eggs in a year, this production being spread over 

 the period of from sometime in February to September or Octo- 

 ber. In this physiological complex are involved the elaboration 

 and deposition of yolks, the rapid growth of a few oocytes just 

 preceding ovulation, ovulation itself, the activation of the ovi- 

 duct, etc. The details of some of the processes involved have 

 been described elsewhere (cf. Rubaschkin (44), Sonnenbrodt 

 (48), Pearl and Curtis (33) and Pearl and Surface (37)) and 

 do not concern us here. The essential point to be noted is that 

 in this normal ovulation factor we are dealing with the basic 

 physiological processes of normal 'unimproved' laying. To 

 make a normal laying hen it is necessary to have present both 

 the anatomical basis discussed above and the physiological basis, 

 which has been designated the normal ovulation factor. 



It is a fact well known to poultrymen, and one capable of 



''^ I give this scientific name with much hesitation, not knowing what 

 pranks the rule of priority or other nomenclatorial disturbers of the 

 peace may have played with it in recent years. In any event the common 

 name will quite sufficiently indicate what bird it is that is here under 

 discussion. 



