THE LEAF. 



245 



to the case of Goebel's cyclamen whose adventitious 

 leaves may be the precocious formations of otherwise 

 latent shoots ; these are known to occur from time to 

 time on the tubers of mature plants. 



Ross describes remarkable formations having the 

 character of clusters of tiny leaves with typical internal 

 leaf- structure which arise adventitiously from the 

 layer below the palisade-tissue in the neighbourhood 

 of a vein on the upper side of the foliage-leaves of the 

 Melastomaceous plants Conostegia and Miconia. They 

 are due to the presence of the eel worm Tylenchus in the 

 tissues of the leaf. These structures may be regarded 

 as belonging to adventitious shoots which have not yet 

 come into being. On the lower side of the leaf and 

 arising from the hypodermal layer, he observed clusters 

 of semi-leaf -like structures which he terms "galls," as 

 their internal structure is not leaf-like. They may 

 quite well be leaves in rudimentary form. 



In Aspidinm angulare var. Lang describes single 

 leaves arising on the proth alius, either entirely alone 

 or side by side with a stem-apex : another example of 

 the same phenomenon. 



All these facts of precocious and, therefore, dominant 

 leaf- formation tend to support the phy ton-theory. 



BIBLIOGRAPHY. 



Goebel. — Einleitung in die experim. Morphologie der Pflanzen, 



p. 205. Berlin, 1908. 

 HiJiDEBRAND, F. — u Ueber eine eigentiimliche Ersatzbildung 



an einem Keimling von Cyclamen Miliar -ahisii und einem 



anderenvon Cyclamen creticnm. >} Ber. deutsch. hot. Ges., 



vol.xxiv (1906), p. 39. 

 Lang. — " On Apogamy and the Development of Sporangia 



upon Fern Prothalli." Phil. Trans. Roy. Soc., ser. B, vol. 



cxc (1898), pp. 187-238. 

 Radlkoper. — Berichte iihev die Thatigkeit des baierischen 



Gartenbau Gesellschaft, vol. i (1862), p. 74. 

 Ross, H. — "Adventivblattchen auf Melastomaceenblattern, 



verursaclit durcli parasitisch lebende Alchen." Ber. 



deutsch. hot. Ges., vol. xxx (1912), pp. 346-361. 



