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tophyte. Usually this gametophyte is considered a morphological 
unit. One can hardly deny, however, that it is of a complex 
nature and that its morphology has to reckon with the following 
processes : 
_ Chromatine-reduction. 
Megaspore-formation. 
. Polarisation. 
Development of a micropylar group of nuclei. 
-. Development of a chalazal group of nuclei. 
- If we want to obtain results of phylogenetical value we have 
got to study the morphology of each of these processes in detail. 
Courter and his school identified chromatine-reduction and mega- 
spore-formation, and likewise Exnst mixed up two lines of deve- 
lopment when basing his system on the total number of nuclei, 
without paying any attention to their origin. Of course it is 
quite possible that there exist connections like those suggested 
by Covnrer and Ernst, but there is no good in presupposing 
them. If they exist they will come to light even when treating 
the processes separately. 
We will first discuss chromatine-reduction and polarisation. 
These two seem to be processes of great constancy and are very 
seldom, if ever, affected by deviation from the normal. 
Reduction division. 
For years this process has been one of the main objects of 
cytological research. It is not necessary to give a description 
in detail of the phenomenon, the more since it is apparently 
without any phylogenetical value. With the few exceptions, 
presented by apogamous plants, reduction division always occurs 
immediately after the formation of the embryosac-mothercell. 
The process is not affected by deviations in megaspore forma- 
_tion, and seems to be of the utmost constancy. It goes on In 
embryosac-mothercells, resulting in four megaspores, as well as 
in embryosacs derived from the mothercell without any mega- 
spore formation. 
Polarisation. 
It is really astonishing that a phenomenon go obvious as 
