1441 
symmetry operations. Each kind of groups as f.i. {2} contains one 
group for each value given to ”. In another paper a list of these 
kinds of groups will be given. ') 
Finally still the remark that not in all cases that may be found, 
the nucleus must remain at rest. *) 
1) Physik. ZS. 22, p. 457, 1921. 
4) In contrast with the theory of space symmetry, which has a mathematical 
character the theory of space time symmetry must be regarded as having a 
mechanical nature. Born, Lanpé and Mape.une (see for the literature Comm. 
N°. 7a) have already started with the subdivision of this theory called by them 
dynamics of atoms; then the preceding might be regarded as an introduction to 
the kinematics of atoms. 
93* 
