DEVELOPINIENT OF JACANA 305 



to see in a bird with an evenly balanced use and development 

 of both limbs, as is found in many Passeres and others. The 

 leg commences to grow with rapidity, however, before the 

 embryo hatches, so that in the very young chick we find it 

 almost proportionally as long as in the adult. The elonga- 

 tion at this time is greater than in any long-legged bird I 

 have examined. 



As time advances the legs continue to lengthen until 

 the chick is more than half grown ; then comes a slackening, 

 while the wings commence to elongate and put on their flight 

 feathers. Until shortly before this period, they had re- 

 mained practically at a standstill — little insignificant, use- 

 less, downy appendages. The little brown-striped bird with 

 gigantic legs, having until now no need for wings, success- 

 fully hides among the stalks of rice and heavy matted grass 

 that cover the savannah, or plimges into the thickets of reeds 

 that line the inland pools. 



The necessity for flight at length arises, for the bird 

 must hunt farther afield in search of food, and the dense 

 grass impedes its progress. With its increasing size and 

 somewhat awkward gait the nearby vegetation does not al- 

 ways offer such a safe retreat as before; so the wing grows 

 and with it the feathers for flight; and the flight, though 

 never strong, serves its purpose well. 



Thus in the development of the jacana, from hatching 

 to maturity, there are two significant phases : the first, where 

 the chick is practically wingless; the second, where the 

 wings play their functional part. Here again Nature's hand 

 is apparent and because of environment, color, habits, need 

 for strong legs and apparent lack of use for wings, these 

 members remain small and weak through the earlier stages, 

 and strengthen later only as need requires. 



THE WING 



The accompanying curve, (Fig. 101 ) , is drawn to show 

 the variations that take place in the three constituent seg- 



