ee 
Hh 
° 
15 
milla, in which species a row of four is quite normally 
formed, without any reduction in the number of chromo- 
somes. It seems hardly possible not to homologise this row 
of four with the ordinary row of four megaspores, especially 
since one of the four develops to a normal 8-nucleate embryosac. 
. Against the assumption that cellwall-omission should induce 
the development of two or more megaspores in the same 
cell, was moved the fact that no cases are known of four 
unquestionable megaspores, lying in the same cell and de- 
veloping all four to form one embryosac of the usual 8-nu- 
cleate type. On the contrary it is difficult to see why four 
developing megaspores should arrange their nuclei into two 
groups (a micropylar and a chalazal one), just as in an or- 
dinary monosporical sac and without leaving any trace otf 
the tetrasporical origin. 
. Against the assumption that the number of nuclei in the 
full-grown sac should be of no importance at all, was moved 
the fact that the 8-nucleate sac is of such remarkable fre- 
quency, that its appearance cannot be believed to be mere 
chance. The less so since (according to Courrer) these eight 
nuclei represent either the greatgranddaughters (in mono- 
spor. sacs), or the granddaughters (in bispor. sacs), OF the 
daughters (in tetraspor. sacs) of the megaspore-nuclel. 
Ernst’s opinion. 
Ernst (1908a, 1908b) rejecting Cov.rEr’s view and all clas- 
sification based on the number of divisions points out ape 
1°. Two distinct processes can be recognised in the life history 
of the gametophyte, viz. embryosac-formation and embryosac- 
development. “Die Entwicklungsvorgange im Embryosack 
scheinen mir unabhingig von seiner Entstehung betrachtet 
werden zu missen.‘ “Die finf Teilungen gehéren ja ganz 
verschiedenen Entwicklungsvorgingen an.” * Die beiden ersten 
reprisentieren die letzten Tetlungen in emmem og aiaicicled ae 
und gehéren dem Vorgang der Sporen bildung an. “Die 
drei anderen Teilungen dagegen erfolgen 1m Verlaufe der 
Sporenkeimung* (1908b, 8. 26). 
