306 



The function of bearing flowers and fruits is not restricted to branches bearing 

 mature leaves solely. Jt is by no means rare on branches which have juvenile leaves, 

 and which causes a strange appearance on branches which have both juvenile and 

 mature leaves. Such an anomaly. 1 believe to be the result of an injury: in other 

 words the branch is beginning its physiological life again, and so we may have, on a 

 tree, a kind of botanical /, in imperio. This trauma may be caused by animals 



or by wind or other meteorological phenomena. 



Indeed, when we see what appear to be abnormal leaves on a branch,, i.e., usually 

 broader leaves, we should consider the possibility that we may have an illustration 

 of Diels's law. An incidental result of such apparent abnormality may give us illus- 

 trations of the equivalents of juvenile leaves, which may serve our purpose when we. 

 cannot get them from early leaf growth in the ordinary way. 



Diels's Law will be found to have a really practical value to the taxonomist, 

 in a genus in which the juvenile leaf plays such a prominent part in classification. 

 It enables us to have a second chance of getting a juvenile leaf, i.e., as the result of a 

 trauma or other stimulus, where the leaf may be flowering or fruiting or not, or otherwise 

 concealed amongst the mature foliage. 



If the figures and Plates (as indicated) of the following species be referred to, 

 it will be found that they indicate examples illustrative of Diels's Law. The names 

 should be compared with the list given at Part XLIX, pp. 275-278, which includes 

 some species which appear to illustrate Nanism, in absence of the specimens or notes 

 on them, and some which certainly do. I believe, however, that a number of the species 

 referred to in Part XLIX illustrate Diels's Law as well, other than those I have 

 selected. 



I have observed Diels's Law in so many species now that I think it will probably 

 be observed eventually in all species. 



In the following references, the species is given first, in alphabetical order, and 

 the figures and Plates of the present work iu brackets : — 



E. alba (Plates 105-107), Part XXV. 



/:'. aUior (figs, la-lg, Plate 44, Part IX), Blackheath, J.H.M., January, 1905. 



E. Beyeri (figs. 1-2, Plate 199, Part XL VIII). We may have a case of flowering 



in the juvenile leaved stage in E. Beyeri. 

 E. BldkebyHfep. 1-2, Plate 134, Part XXXII). 



/;'. Bosistoana. See Part XLIX, .p. 275, and also present Part, p. 270. 

 E. calophyUa. Often flowers in the peltate (young) stage. 

 E. calycogona (fig. I), Plate 9, Pan IU). Intermediate. Not quite juvenile 



leaves are shown i Sgure. 



E. celastrm _. B, Plate 10, Pari HI). 



/:. cmerea (Pla1 I and 90, Part XXI). 

 /•/. Cooperiana (fig. 6, Plate 151, Pari XXXVI). 

 /:'. curiacm (fig. I". Plate 27, Part V). 



