�@Periodic minimal surfaces have been studied by many researchers. <BR>
In particular, (i) Y. Nagano - B. Smyth's and W. H. Meeks' 
works are basic theory about that, 
(ii) Recently, the Moduli space of the minimal surfaces in 
flat tori has been studied by C. Arezzo and G. P. Pirola.<BR> 
�@Our main object is holomorphicity of minimal surfaces.  
This has been studied by M. Micallef - C. Arezzo, and 
they use Algebraic Geometrical method. 
In this talk, I'd like to introduce the surveys of 
minimal surfaces in 3 or 4-dimensional flat tori by means of 
the theory of classical Gauss map.