SECT. 2] 



AND WEIGHT 



Table 62. BergtoWs figures (cont.). 



479 



Gurney's theory was that incubation time depended on longevity. 

 The view of Gadow — at first sight more acceptable — was that the 

 developmental period as a whole was uniform and the longer the 

 Qgg period the shorter the nest period. Yet this simply raises another 

 question, and while it is more difficult to determine the total develop- 

 mental period than the incubation period alone, the difficulty of 

 relating the preparatory period, whatever it is, to the causal factor, 

 still remains. No doubt the differences between nidicolous and 

 nidifugous birds are removed by this means. Glaus' theory was that 

 incubation period depended on egg-size, i.e. egg-weight, but this 



