SECT. 2] 



AND WEIGHT 



477 



the weight of a bird is muhipHed one thousand times, the incubation 

 period will only be prolonged about four times. Similarly if the egg- 

 weight is increased by one thousand times, the incubation time is only 

 prolonged four times. No doubt this does not take us very far, but 

 it is always a step forward to have all the information on one graph. 



Table 62. Bergtold's figures. 



* Haswell gives 84 days and 21 oz. for this bird. 



