Fhlk : CONTRllSUTION TO THE LIFE-HISTORY OF RU.MEX. 145 



the last plants that the two polars fuse in the lower part of the 

 sac, the larger gamete strangely enough traveling further than 

 the smaller and thus showing greater activity. Mottier * finds 

 them of about the same size in Scnccio aureus and that they 

 fuse in the anterior end of the sac just below the ^%%-, the lower 

 of the two equal-sized polars thus showing greater activity. In 

 Rumex, and all of the Polygonaceae so far as studied, the two 

 polar nuclei are of about the same size (Figs. 15, 17 and 20) 

 and fused at or near the center of the sac. 



During the passage from the four-nucleate to the eight-nucle- 

 ate condition, the sac increases considerably in size (comp. Figs. 

 13 and 15), and the increase in size is even more noticeable as 

 the sac matures (comp. Figs. 15 and 24). 



The Mature Embryo Sac. — The mature sac contains typically 

 the usual seven nuclei, though in Rumex verticillatus, as stated 

 elsewhere, the number in the antipodal region may vary, pro- 

 ducing a corresponding variation in the total number contained 

 in the sac. In Rumcx zrrticillatus the synergidse are some- 

 what irregular in form (Figs. 19 and 23), while in Rumex 

 salicifolius they are more regular in outline (Fig. 24). The 

 egg usually lies in contact with the lower part of one synergid 

 in both plants (Figs. 19, 23 and 24), and its nucleus is much 

 larger than those of the synergidfe. All three nuclei are en- 

 closed in definite walls at this time. The definitive nucleus is 

 much the largest nucleus in the sac (Figs. 18, 23, 24, 25 and 

 28). In Rumex verticillatus it usually approaches the ^^^ 

 after formation and lies close to it till the time for fecundation 

 approaches (Fig. 23) when it commonly recedes somewhat 

 (Figs. 25 and 26). In Rumex salicifolius it usually lies at 

 some distance from the Qgg in the mature sac (Fig. 24) though 

 it was once seen nearer in an earlier stage (Fig. 22). In Ru- 

 mex salicifolius it may be assumed that the antipodals are in the 

 typical three-celled condition at^naturity as they were observed 

 in this condition both before and after as already stated (Figs. 

 17 and 33). As before noted the condition of the antipodals in 

 Fig. 24 is doubtful. The condition of the antipodals in Rumex 

 verticillatus at this time has also been explained above. 



In shape the mature sac in both plants differs quite widely 

 from that of Polygonum divaricatum as shown in Strasburger's 



* Mottier, David M. On the Embryo Sac of Senccio aureus. Bot. Gaz. i8 : 

 Fig. I and p. 248. Jl. 1S93. 



