A model is proposed for the formation of clouds of the La forest. Earlier calculations have shown that the UV emission from hot stars must play an important role in the reionization of the pregalactic medium (PGM). The formation of galaxies therefore occurred simultaneously with PGM ionization, and the reionization process was nonlinear. With allowance for this fact, the Gunn-Peterson effect, and the fact that galaxies exist at z ≈ 5, which follows from observations, we can conclude that galaxies began to form earlier, perhaps at z ≥ 10. The observed presence of heavy elements in La -forest clouds is evidence that these clouds were formed later than galaxies — from interstellar clouds ejected by galactic wind. The next generation of galaxies might have resulted from an increase in the masses of La -forest clouds due to their merging.