211 



locality mentioned abov^e, as a real-estate company is at present 

 engaged in laying out an addition in the field in question. 



Kenneth K. Mackenzie. 



49 Wall St., New York City. 



Further Note on the Formation of aerial Tubers in 

 SoLANUM. — In connection with the article on "Tuber-formation 

 in Solaiiuiii tiiberosinn in Daylight," in the preceding number of 

 ToRREYA, two recent illustrated papers,* not referred to in that 

 article, are of considerable interest. 



Referring to the fact that the production of aerial tubers by S. 

 tiiberos2im has been repeatedly noted in scientific journals and 

 horticultural publications (no references are given), Vilmorin 

 states that he himself has observed it in the varieties " Cardinal," 

 "Giant Blue," and the "Wonder of America." The anomaly is 

 more apt to occur on varieties having colored tubers than on 

 those having white ones, and the aerial tubers form preferably 

 when the vegetation is exuberant on account of the moist condi- 

 tion of the soil. They arise, he says, " on the lower part of the 

 stem in the axils of the leaves, and resemble secondary branches 

 hypertrophied and swollen with reserve food. Furthermore, if a 

 branch of a given variety of potato is buried, tubers will form at 

 that region before the plant has produced them on the subter- 

 ranean branches properly so-called." 



It is also stated (again without exact reference) that another 

 observer saw a plant that had all the specific characters of 

 Solamim ttibei'osimi L. give rise to an authentic tuber of ^S". Coiii- 

 viersoni Dunal. " If," says Vilmorin, " that was its exact origin, 

 which I do not yet believe, we have without doubt to consider a 

 problem very interesting for botany and very disquieting for 

 nomenclature : the spontaneous passage of one species into 

 another without the crossing of a single sexual generation." 



Such an extraordinary case of discontinuous variation should 

 be authenticated by the strongest evidence. 



* Vilmorin, Ph. L. de. Sur les tubercules aeriens de la Pomme de terre. Bull. 

 Soc. Bot. France 52: 535. 1905. 



Labergerie, M. Tuberisation des Tiges aeriennes des variations du Solanum 

 Commersoni. Ibid., 53 : 179. 1906. 



