POSITIVE DEDOUBLEMENT. 



59 



Dietz. — " Beitrage zur Kenntiiiss der teratologisehen Falle 

 cles Mais." Bot. CentralbL, Jahrg. iii, Bd. x (1882), 

 pp. 413-415. 



Dutailly. — "Anomalies dans l'epi femelle du Mais." Bull. 



mens. Soc. Linn., Paris, tome ii (1892), pp. 1051-1053. 

 Harshberger. — "Maize, a Botanical and Economic Study. " 



Contrib. Bot. Lab. Pennsylv., vol. i (1892), pp. 75-202; 



pis. xiv-xvii. 



"A study of the fertile hybrids produced by cross- 

 ing Teosinte and Maize." Loc. ctt., vol. ii (1898), pp. 

 231-235. 



Krafft. — Die normale und anormale Metamorphose der Mais- 



pflanze. Wien, 1870. 

 Peirson. — "Abnormal Development in Maize." Journ. But., 



vol. xlix (1911), p. 34. 

 Penzig. — " Studi morphologici sui cereali. I. Anomalie 



osservate nella Zea Mays." Boll. Staz. Agr. Modena, 



n. s., Ann. iv (1884). Pes. in Bot. CentralbL, Bd. xxiii 



(1885), pp. 353-354. 



Pflanzen-Teratologie, Bd. ii. Genua, 1894. 



Schur. — " Beobachtungen in der Flora von Siebenbiirgen." 



(Ester, bot, Zeitschr., Jahrg. ix (1859), pp. 11-12 



[Maize]. 



Watson, S. — "Upon a Wild Species of Zea from Mexico." 

 Proc. Amer. Acad. Arts and Sci., vol. xxvi (1891), pp. 

 158-161. 



4. POSITIVE DEDOUBLEMENT. 



This is a term borrowed from the writings of Cela- 

 kovsky. When the tendency for an organ to divide 

 becomes all-potent, overriding completely that which 

 makes for unity, the result is the formation of two 

 organs instead of one : this is positive dedoublement. 

 It has been usually applied to the phenomenon termed 

 by many authors " polyphylly," viz., the increase in 

 number of the members of a floral whorl. But it may 

 equally well be applied to the phenomenon of " pleio- 

 taxy," or the increase in number of the whorls of a 

 flower, and in this dual sense it will here be used. 



The phenomena of positive dedoublement in the 

 abnormal cases considered in the following pages may 



