ratio could serve as a description of the shower development stage just as well. But we shall stay with the tradition and use formula (1) for it.\
The state of an electron at some age $s$ can be described by four variables: the electron energy $E$, its distance to the shower axis in $\mathrm{g/cm}^2$ or in $r/r_M$, where $r_M$ is the Molière radius at the depth $X(s)$, and the two angles of the electron direction with respect to the shower axis, the polar angle $\theta$ and the azimuth angle $\varphi$. Thus, our main conclusion reached in this paper for the first time, means that the five dimensional function $f(\theta,\varphi, r/r_M, E;s)$, representing the shape of the four-dimensional electron distribution at any level $s$, is the same for any shower, i.e. it has a universal dependence on the five variables (Section 2).\
This conclusion could be drawn for showers having enough electrons in small cells of the four-dimensional space of the variables $E, r/r_M, \varphi, \theta$ at various levels $s$, so that the function $f(\theta,\varphi, r/r_M, E;s)$ could be determined. This limits the shower primary energies to be greater than $(10^{16} - 10^{17} )$ eV, depending on the choice of the 