388 



Gihb : The Study of a Fircone. 



stamens and pistil — for a new purpose. So the flowers of 

 Pittosporium undulatiim and of the rose have their parts in 

 fives, corresponding with their leaf arrangement in a series of 

 five. Here again, however, it must be remembered that cir- 

 cumstances often change and confuse the issue, and not in every 

 case can the story be easily read. 



If an effort be made to find the perfect series of phyllotaxian 

 numbers in the diagram of the common holly, given above, 

 the result will probably be puzzling. In order to do so it is 

 necessary to break into the series of its leaf-arrangement and 

 begin at the end of the first coil. Since 

 the series runs : 3, 3, 2 ; 3, 3, 2 ; it 

 will now read 3, 2 ; 3, 3, 2 ; 3, 3, 2 ; 

 and so on ; and the coil will pass 

 three leaves in one turn, five in two 

 turns, eight in three turns, thirteen in 

 five turns, and twenty-one in eight 

 turns (1, I, |, ^%, -ij). 



Now the fircone is built on just the 

 same general principles as these which 

 I have been endeavouring to make 

 clear ; only in its case ^^ is the order 

 of its leaves ; that is the coil, if pulled 

 out by the yard so as to shew its true 

 formation, would be seen to pass 

 through twenty-one scales in eight 

 coils before one scale would be found 

 growing exactly over the first, and the 

 time of its rhythm is 3, 3, 2, 3, 3, 2, 

 3. 2 ; 3. 3. 2, 3, 3, 2, 3, 2 ; repeated 

 endlessly as with the others. 



Looking at the drawing of a fircone 

 (fig. 3), with numbered scales, shewing the order of the hidden 

 spiral which passes through them all, it will be seen that the 

 twenty-second scale stands just above the first, and the com- 

 pression of the cone is brought forcibly forward by that fact, 

 for within that short space the original spiral has made no 

 fewer than eight coils, passing through twenty-one scales in its 

 way. 



Fig. 3. 



Shewing the manner of 

 formation of secondary 

 spirals on a spruce fir- 

 cone having 8 spirals 

 going to the right and 

 5 to the left. 



{To be continued). 



Naturalist, 



