THE OVULE OF IMPATIENS 203 



nucellus are tracheid-like and meet a group of similar cells in the 

 funiculus. Of the four axial megaspores, the chalazal one de- 

 velops at the expense of the other three. The gametophyte 

 number of chromosomes is probably twelve. The egg-apparatus 

 is unusual in that the egg lies below the synergids. The antipo- 

 dals are very transitor^^ The endosperm, which nearly fills the 

 sac, produces an haustorial protuberance into the micropyle 

 which first appears when the endosperm begins to be formed. 

 Longo interprets a similar structure in Impatiens ampkorata and 

 7. 7'oylei as nucellar tissue, but there is good evidence that it is 

 endosperm. The endosperm is displaced by the developing 

 embryo. 



TECHNIQUE 



The material was fixed in several different lots, corrosive sub- 

 limate solution being used for some, chromic-acetic acid solution 

 for some, and a weak chromic-acetic with osmic acid for still oth- 

 ers. The slides were cleared with xylol and mounted in balsam. 



The most successful stain for the meristematic tissue was 

 Delafield's Haematoxylin, and it was best when it followed cor- 

 rosive sublimate fixing solution. For mitotic stages Heiden- 

 hain's Iron-alum Haematoxylin was used, usually in combination 

 with Orange G., safranin gave good results as a stain for embryo- 

 sacs. 



All of the figures except D, F, G, and H were made with the 

 camera lucida. 



This paper is the result of work done under the direction of 

 Prof. H. i\I. Benedict, to whom the author is indebted for help 

 and suggestions. Thanks are also due to the Lloyd Library and 

 to the Librarians for the use of literature. 



