FLORAL SYMMETRY. ETC. 



125 



called a leaf-cycle; that is, the distance in a spiral 

 line around the stem, from one leaf to another placed 

 exactly above it. 



FIG. 272. 



Holding the string in place, observe, first, how 

 many times it has wound around the stem ; and, sec- 

 ondly, how many leaves it passes on its way. If, in 

 passing from the first leaf to the one directly over it, 

 the string makes but one circuit around the stem, and 

 the third leaf is over the first, so that the cycle in- 

 cludes but two leaves, the fourth leaf being over the 

 second, and so on, you have an arrangement like that 



