310 THE STRUCTURE OF FLOWERS. 



" Les bulbilles des Amaryllidees ne sont pas toujours des 

 graines veritables modifiees seulemenfc quant a I'epaisseur et 

 a la consistance de leurs diverses couches natarelles, notam- 

 ment des plus exterieures. Temoin le Calostemma Gunning- 

 hamii. Ici, par une singuliere transformation de I'ovule en 

 bulbe, la chalaze, en s'epaississant, joue le role d'un veritable 

 plateau, sur lequel se produisent une, puis plusieurs racines 

 adventives. Les enveloppes ovulaires tienne alors lieu 

 d'ecailles bulbaires tandis qu'il s'eleve dans le sac embryon- 

 naire un veritable bourgeon parti de la chalaze comma 

 support et s'echappant par son sommet de la cavite ovulaire 

 pour se comporte ensuite comme une plante complete." 



An analagous case of bulbs arising from a foliar organ 

 occurred with Scilla Sihirica. Some plants dug up in October, 

 1887,* were found to have taken the form of the so-called 

 " droppers " not uncommon in tulips. Their peculiarity 

 resides in the fact that the tubular leaf-sheath bends and 

 grows downwards, thereby carrying the axillary bulbil to a 

 greater depth in the soil than usual. In February, 1888, on 

 re-examining them. Dr. Masters discovered that from one to 

 four bulbils had been developed at different heights within 

 the tissue of the tubular sheath, being in connection with the 

 cords of the latter by means of a transverse nexus of tracheids. 



I refer to these cases as being curious instances of axial 

 structures proceeding from foliar — i.e., by the change of 

 character of the fibro-vascular cords from being at first 

 foliar and then axial. They support the theory of homology 

 of leaf and axis, w^hich is, of course, otherwise quite efficiently 

 substantiated by such plants as Xyloiohylla, Buscus and the 

 Oactacece. 



* Gard. Chron. for Oct. 15, 1887, p. 475, fig. 98, " droppers ; " also, for 

 March 3, 1888, p. 276, fig. 45, ditto, with bulbils. 



