152 



BOTANY. 



parasticliies passing to the right, while leaves 3, 6, 9, 13, 

 15, 18 belong to the parastichies which pass to the left. 



(5.) Upon counting, 

 in Fig. 129, it is found 

 that there are three 

 parastichies passing to 

 the left and five to the 

 right ; the smaller 

 number is the same as* 

 the numerator of the 

 fraction expressing the 

 angular divergence, 

 while the sum of the 

 two equals the denomi- 

 nator ; similar rela- 

 tions may be shown to 



Fig. 130. — Diagram of eight-ranljecl arrange- • , . , . 

 ment, viewed from above. The orthostichies, whicli eXlSt in Qtner CaSeS. 



200. — If now we 

 study the several ar- 

 rangements by projecting the stem upon a flat surface in 

 such a way that the successive 

 nodes, in ascending the stem, 

 are represented by smaller 

 and smaller concentric circles 

 (Fig. 130) (as would, in fact, 

 be the case if we made sections 

 through the nodes of the 

 punctum vegetationis), it is 

 at once evident that each leaf 

 is so placed as to stand over 

 the vacant space between the 

 j)reviously formed ones, and 

 that as regards the, leaves 

 formed after it, it is equally 

 well situated. 



Hofmeister formulates this 



here appear to be radial iines, are numbered, as in 

 Pig. 129, from I. to VlII The leaves are number- 

 ed from 1 to lb. — After Sachs. 



Fig. 130a. — Cross-section of a leaf-bud 

 of the Hemloclc Spruce ( Tmiga Canaden- 

 sis). Magnified.— After Hofmeister. 



to tlie morphologist. So much has this been done, that the study of 

 Phyllotaxis has in some quarters become little more than a species of 

 mathematical gymnastics. 



