156 PRINCIPLES OP PLANT-TERATOLOGY. 



be noted that in the autumnal hawkbit (Leontodon 

 autumnal is) tiny involucral bracts extend a long way 

 down the scape ; in the Leontodon -scape figured by 

 Masters the abnormally-placed leaves are foliaceous. 

 The ancestral state of the shoot must have been a leafy 

 one, and the naked condition has arisen owing to some 

 special adaptation. All the above are clearly, therefore, 

 cases of reversion. 



It is probable that in those plants in which a marked 

 difference obtains between the shape of the radical 

 and that of the cauline leaves, this is a secondary 

 phenomenon, and that originally the leaves borne on 

 different parts of the axis were much more alike, or 

 that there was not such a well-marked basal rosette as 

 there is at present ; hence we may regard as a species 

 of reversion the case described by Goebel of a hare-bell 

 (Campanula rotmidifolia) which bore all up its flowering- 

 stem the semi-orbicular leaves normally occurring at 

 the base only. 



3. Saroody of Scale- leaves. — There was described 

 in the 6 Gardeners' Chronicle ' a rare abnormality in 

 Crocus consisting in the transformation of the brown, 

 membranous scale-leaves at the base of the aerial stem 

 into fleshy scale-leaves like those composing the bulb 

 of a lily or hyacinth. The change was the more re- 

 markable from the fact that Crocus does not normally 

 possess such fleshy bulb-scales. In correlation with 

 their formation in this case the foliage-leaves w^ere 

 small and the flower was imperfectly developed. 



4. Phyllody or Scale-leaves. — The transformation 

 of scale-leaves to foliage-leaves is a very much rarer 

 phenomenon. In the axils of foliage-leaves of the 

 potato, owing to prevention of the normal underground 

 tuber-formation (but also occasionally when this is not 

 thwarted), small tubers develop bearing small foliage- 

 leaves and transitions between these and the ordinary 

 scale-leaves. 



A very good instance of the phenomenon is afforded 

 by a plant of a butcher's broom (Ruscus androgynus) 



