io6 



PHYSIOLOG Y. 



215. How the first leaf appears. As the embryo backs out 

 of the seed, it turns downward into the soil, unless the seed 

 is so lying that it pushes straight 

 downward. On the upper side of 

 arch thus formed, in the petiole 

 the cotyledon, a slit appears, and 

 through thif ~pening the first 

 arches its way out. The loop of 

 petiole comes out first, and the 

 later, as shown in 

 fig. 98. The petiole 

 now gradually 



the 

 of 



leaf 

 the 

 leaf 



Fig. 98. Fig. 99. Fig. 100. 



Seedlings of jack-in-tlie- Embryos of jack-in-the-pulpit Seedling of jack-in- 



pulpit, first leaf arching still attached to the endosperm in the-pulpit; section 



out of the petiole of the seed coats, and showing the simple of the endosperm 



cotyledon. first leaf. and cotyledon. 



straightens up, and as it elongates the leaf expands. 



216. The first leaf of the jack-in-the-pulpit is a simple one. 

 The first leaf of the embryo jack-in-the-pulpit is very different 

 in form from the leaves which we are accustomed to see on 

 mature plants. If we did not know that it came from the seed 



