242 



RAYMOND PEARL 



cycles. Each day's *n' in the record of such a bird represents an 

 eggi5 which she would have laid, had she been physically capable 

 of so doing. 



Birds in which the oviduct is occluded through some diseased 

 condition often behave in this same manner. It may result 

 from other abnormal conditions also. With this explanation, 

 the following record of 9 558, will be clear, it being understood 

 that '?i' denotes a visit to a nest and the performance of those 

 acts characteristically associated with the laying of an egg, but 

 without the extrusion of an actual egg. 



Fig. 3 Nesting record of 9 558. 'n' denotes a visit to the trap-nest, n^ 

 indicates that the bird visited the nest twice on the same day. B indicates that 

 the bird became broody, and that she ceased manifestations of broodiness. 



From this record taken in connection with other similar cases 

 studied in this laboratory, there can be no doubt that 9 558 

 belongs gametically in the class 'Under 30.' 



Another point is with reference to the mating & 564 X 9 405. 

 The excess of 'Over 30' birds here is in part due to the fa'ct that 

 two birds, which have winter records respectively of 32 and 34 

 eggs and are almost certainly to be regarded as somatic fluctua- 

 tions above the division point at 30 are included in the ' Over 30' 

 class. 



'^ Of course this does not mean that when a bird visits a nest twice in the same 

 day she would have laid two eggs that day had she been normal. Many laying 

 birds have the habit of visiting the nest once or twice in the same day before actu- 

 ally laying. 



