94 ORGANOGRAPHY. BOOK I. 
Pinus pinaster, ti — sylvestris, — cembra, o^j — larix, ^ 
— microcarpa f. 
Betula alba and pubescens, and — fruticosa gene- 
rally, -^3. 
Corylus avellana, 2t — americana and tubulosa, ^ J in their 
male catkins. 
The whole of this curious question has been greatly simpli- 
fied by Professor Henslow, in observations printed some 
months ago for private circulation ; and we are happy to be 
able, by the permission of their liberal author, to lay them in. 
this place before the public. 
" The scales on a cone of the Spruce Fir (Abies excelsa) are 
placed spirally round the axis, at equal intervals ; and after 
eight coils of the spiral, the twenty-second scale ranges verti- 
cally over the fiist. If this arrangement be referred to a 
cylinder, and then projected on a plane cutting jts axis at 
