> 
or 
° 
fe) 
11 
logising purposes. Unquestionable cases of desintegrating cell- 
walls are known as well as cases of total suppression of the 
megaspore-cellwalls. For instance Me Arzister (1909, 1914) 
states that cellwalls originally formed between the mega- 
spores of Smilacina and of some of the other Convallariaceae, 
soon break down and finally disappear. And Smrrn’s (1911) 
description of Clintonia shows four megaspores in the same 
cell, there being never more than a small trace of cellplate- 
formation. 
. The number of nuclei in the fullgrown sac has no phylogenetical 
or systematical significance at all. 
Fig. la shows plainly enought that the 8-nucleate stage of 
a “tetrasporical sac‘, the 4-nucleate stage of a “bisporical sac*, 
and the 2-nucleate stage of an ordinary “monosporical sac“ 
are considered to represent the same stage of development. 
So there is no sense in phylogenetical hypotheses or in 
systems, based on the number of nuclei. 
. The number of divisions from the embryosac-mothercell up to 
the egg furnishes the most valuable data for phylogenetical and 
systematical siudies. 
One of the most striking facts in the evolution of the 
vegetable kingdom is the continuous shortening of the ga- 
metophyte-generation. Among Gymnosperms numerous divi- 
sions of the megaspore-nucleus are still prevailing. Within 
the Angiosperm group however this number has been reduced 
greatly. Normally it is only three, making a total number 
of five divisions from the embryosac-mothercell up to the 
ege. A total of four or three divisions is also known and 
theoretically the possibility of only two divisions (megaspore- 
nucleus = egg: the animal condition) must be admitted. 
The smaller the number the more advanced the type. The 
occurence of more than five divisions on the other hand 
should indicate a more primitive condition. 
It must be observed here that neither the idea of identifying 
megaspore-formation with chromatine-reduction, nor the idea 
of using the number of divisions for phylogenetical purposes, 
