to believe that a species would be better able to successfully 

 maintain its status in the face of its daily dangers, through 

 the increased prolificity made possible by the short incuba- 

 tion period permitting more, and perhaps equally large 

 broods to mature during the breeding season; this is but 

 another way of making the eggs proportionate to the dan- 

 gers meeting the species in its daily life, and may be looked 

 upon as a result of the higher birds having high temper- 

 atures. 



More broods each season inflict greater responsibility 

 and labor on the parents; this affects but two, while the 

 greater multiplication of individuals certainly more than 

 counterbalances this. As said above, Gadow holds that the 

 shortened incubation period, and its correlated long nest 

 period ( ? ) reflects benefits on both parents and young ; I 

 believe it does help the young, but as to the parents, I am 

 inclined to feel that for them, the beneficial effects are ne- 

 gated by the disadvantage of more labor, wear and tear, etc. 

 In all other creatures, the parent is so universally disre- 

 garded, so to speak, for the good of the young, that I am 

 skeptical as to there being an exception with birds. The 

 question also arises of two species, which young are better 

 able to fend for themselves at the end of a given time, view- 

 ing the question from the standpoint of the possible bene- 

 ficial or injurious effects of a short or a long incubation 

 period, those hatched after a short or those after a long in- 

 cubation? Two months after hatching are young robins, or 

 young quail, better able to shift for themselves, and to meet 

 and overcome the perils of their daily life? It seems to me 

 that the advantage lies with the higher bird, because of its 

 shorter incubation period, which supports the belief that the 

 diminishing lengths of incubation delivers benefit to the 

 species. It is self-evident that such a continual shortening 

 of the incubation period as I have assumed to have been in 

 progress in the past, and which is probably still going on, 

 may have for a given species adventages and disadvantages 

 which cannot now be clearly apprehended since some may 

 be disappearing and others only just coming into effect. 



If my contention be correct, that the trve length of in- 

 cubation is a fixed and persistently inherited characteristic, 

 and determined by the bird's temperature, and its position 

 in its scale of life, it then becomes possible that this char- 

 acteristic will be useful as an aid in allocating the correct 

 taxonomic position of a species, taking a place (perhaps a 

 very minor one) with anatomy, embryology, splanchnology, 

 ptilosis, etc. ; it seems to me^ that there are larger possibilities 

 for usefulness in these directions for this character, than 

 there are for such an unmeasurable and indeterminate char- 



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