Transformation of Plant Ovule into an Ovary. 135 



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 



If the formation of the basal prolification be due to the presence 

 of special formative substances, one might occasionally expect to 

 find the formation of carpellary tissue from other primordia. 

 The only primordia normally developed subsequent to the carpels 

 themselves are the ovules, which are borne on the carpellary 

 margins. 



To test this point, and to secure materials for other investiga- 

 tions, a series of dissections was begun in 1908. Those which 

 were made from 1908 to 19 15 are summarized in the accompanying 

 table. 



The results show that in the series of 568,098 dissections which 

 have been made of fruits grown under a rather wide variety of 

 conditions, basal prolification occurred 18,921 times, or in 3.330 

 per cent, of the fruits. Placental prolification occurred only 224 

 times or in .039 per cent, of the cases. Basal and placental 

 prolification occurred in 18 of the 568,098 fruits. 



While the occurrence of basal prolification presents a number 

 of interesting morphological problems it does not seem to have 

 the physiological significance of placental prolification. In the 

 first case we have merely the continuation of activity of an axis 

 which normally ceases with the laying down of the whorl of 

 carpels forming the normal fruit. In the second case we have 

 an entire transformation of a primordium. The primordium 

 which should develop into an ovule forms instead a carpel, i. e., 

 one of the units of which the normal ovary is built up. 



I am inclined to consider that this result is due to the local 

 influence of special formative materials. 



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. 



