- The female gametophyte of Angiosperms. 
I. INTRODUCTION. 
Up to the beginning of this century hardly any attention 
was paid to the study of the development of the Angiosperm 
embryosac. Only very few cases of “abnormal sacs“ being known, 
it was generally accepted that the development was of a most 
striking uniformity throughout the whole group. This normal 
course runs as follow: By two successive divisions the embryosac- 
mothercell gives rise to a row of four cells, called megaspores. 
Three of these soon begin to degenerate while the fourth, ra- 
pidly increasing in size, becomes the functioning embryosac. 
Its nucleus divides itself thrice thus producing eight nuclei, 
originally free in the same plasm but soon separated by cell- 
walls. These eight nuclei are arranged into two groups: Viz 
& micropylar one (egg and two synergids) and a chalazal one 
- (three antipodals). In the middle of the sac the two remaining 
nuclei (polar nuclei) are seen fusing (embryosac-nucleus). 
The last fifteen years however have brought to light an ever 
growing number of atypically developing sacs. Deviations in 
almost every direction were detected. First of all the number 
of megaspores seems to vary from the normal four to only one 
(“row of three*, “row of two“ or “embryosac-mothercell func- 
tioning as embryosac‘), Secondly the number of nuclei in the 
fullgrown sac is far from being regular. Instead of the usual 
eight there may be sixteen or only four; not to speak of the 
numerous cases in which a secondary increase or decrease of 
nuclei could be stated. 
Some of these pecularities are characteristic to certain spe- 
