14 



a still further réduction exists in Cypripedium, wliere 

 according to the researches of Miss Pace ') thelower por- 

 tion of the embryo-sac has not even been laid 

 down at ail. It need scarcely be argued, that we are hère 

 concerned with a progressive differentiation, and not with 

 the récurrence of ancestral peculiarities. Perhaps it may 

 not be amiss to point oui, in conclusion that we cannot 

 hère fall back for „explanation" on a parasitic or sapro- 

 phytic mode of life of Fodostemaceae. 



1) Lu la Pace, Fertilization in Cypripedium. Botanical Gazette. 

 XLIV. 1907. p. 353. 



EXPLANATION OF THE FIGURES ON PLATE I. 



Ail the figures represent longitudinal sections of ovules 

 or parts of ovules of the Podoslemwceae, with the exception 

 of fig. 12 and 13. 



i. e. outer integument. — i. i. inner integument. — 

 sp. m. spore mothercell. — m. s. megaspore. — a. n. 

 antipodal nucleus. — s. synergid. — e. egg. — e. s. 

 embryosac. — ps. e. s. pseudo-embryosac. — p. t. pollen- 

 tube. — m. n. maie nucleus. — f. n. female nucleus. 



Fig. 1. Oenone Imthurni. Young ovule, where the curva- 

 ture has just taken place. Nucellus with central 

 row of four cells and epidermal layer. No integu- 

 ments. Mag. X 580. 



Fig. 2. Oenone Imthurni. Young ovule, where the spore 

 mothercell is already differentiated. Half of the 



