[Biological action of an unidentified factor from streptomycetes].

Studied were a total of 926 actinomycetic strains. In 285 of them (27.8 per cent) there was a capacity to synthesize growth factors which stimulated the production of fruit bodies of the mycelial fungus 2x. The culture liquid of two of the producent strains, 210-c and 192-B, was given as a supplement to the ordinary feed ration of albino mice. It was found that birth rate rose twice with the test groups. Histologically, a stimulant action was demonstrated with regard to ovogenesis in terms of the earlier maturation of follicles and formation of corpora lutea both in rats and in 4-5-month-old lambs.