10 
this critical review to those publications which consider also 
the systematical side of the question. 
As stated above there is often, instead of the row of four 
megaspores, a row of three, a row of two, or even no row at 
all. A vivid discussion was started in 1908 by Ernst (1908a, 
19084) on the one and Coutrer (1908) on the other side on the 
question as to which nuclei in these cases ought to be regarded 
as the homologues of the megaspores. Two hypotheses were 
suggested and held up to the present moment. Fig. la and 16 
illustrate the two opposite opinions, clearly showing the diffe- 
rence between Coulter’s and Ernst’s view. 
As most authors refer to these two conceptions we will dis- 
cuss them more fully in essence and consequences. 
Coulter's opinion. 
1°. According to Counrer the nuclei produced by the second divi- 
sion of the embryosac-mothercell-nucleus are always lo be regar- 
ded as nuclei of megaspores. Usually these megaspore-nuclei 
are separated by cellwalls, the developing embryosac thus 
being of “monosporical* origin. Occasionally however the second — 
division, or even the first division too, is not accompanied 
by cellwall formation. In these cases both or all four mega- 
spore-nuclei may develop, the results being “bisporical* or 
“tetrasporical* embryosacs. 
Accepting the consequences of this point of view, CouLTER 
further defends the following principles: 
bo 
*. Megaspore-formation is determined by chromatine-reduction. The 
megaspore nucleus is the first nucleus of the gametophyte, 
i. e. of the n-generation. The end of the 2n-generation and 
the beginning of the n-generation is determined by the pro- 
cess of chromatine reduction. As long as chromatine reduc- 
tion did not occur the nuclei still belong to the sporophyte 
and they can not be called megaspores. 
a) 
° 
: Megaspore- formation is entirely independent of cellwall-forma- 
tion. Cellwall-formation is of only small importance for homo- 
