Reprinted from the Proceedings of the Society for Experimental Biology and Medi 

 cine, 1919, xvi, pp. 134-136. 



75 (1450) 



The transformation of the plant ovule into an ovary. 

 By J. ARTHUR HARRIS. 



[From the Station for Experimental Evolution, Carnegie Institution 

 of Washington, Cold Spring Harbor, N. Y.] 



In plants there is a rather wide capacity for the development 

 of organs of various kinds from primordia normally destined to 

 produce quite different structures. For example, leaves may 

 replace petals, stamens or carpels; petals may occur in the place 

 of stamens or carpels. The transformation of stamens into 

 carpels is a well-known phenomenon. 



Furthermore, the continued development of a growing point 

 the activity of which is usually terminated by the formation of 

 some highly specialized organ, such as the flower or fruit, is quite 

 familiar to those concerned with problems of variation. 



Among these morphological abnormalities the continued 

 meristematic activity of the axis which is normally terminated by 

 the formation of the ovary is of very rare occurrence. It is, how 

 ever, regularly found, although in a small and variable percentage 

 of the cases, in one of the passion flowers, Passiflora gracilis. 

 Here prolification of the fruit consists in the formation of series 

 of carpels, which may or may not be ovuliferous, within the 

 normal fruit. The mass of accessory carpels thus formed may 

 be so large as to rupture the fruit wall. 



While the occurrence of prolification may be regarded as a 

 heritable characteristic in P. gracilis the abnormality is of rela 

 tively rare occurrence. Physico-chemical factors must, therefore, 

 determine the occurrence of prolification in certain fruits and its 

 absence from others. 1 



1 A prolonged effort to demonstrate the nature of these factors has been incon 

 clusive. Subsequent studies have not substantiated in all cases the position taken 

 by Gortner and Harris (Bull. Torr. Bot. Club, 1913, XL., 27). Studies on the os 

 motic concentration and the electrical conductivity of the fluids of the proliferous 

 mass and of the wall have been given by Harris, Gortner and Lawrence, Biochem. 

 Bull., 1915, iv., 52. 



