抄録
Mice were inoculated with the M-type Var. (Mutabile type Variant) of Murase of Salm. typhi-murium and obserbed whether they die of infection by M-type Var. itself or by organisms (Variants) derived from it.
Relatively young mice and adult mice were used for the experiment. Two kinds of M- type Var., one of which was thought to be easily reversible to the original (“RT” of Fukutome et al) than the other, were used for the inoculation.
Experimental results were as follow : The so-called “M”→“RT” mutation rate of the test strains by simple fermentation method in galactose broth were the same as before.
Some of the mice died of sepsis by intraperitoneal inoculation of 10-1 mg of “MA” organisms, but none of them died when 10-2 mg was administered. “MB” strain was found more virulent than “MA” strain. But When 10-1 mg of “MA” strain contained 10-8 mg of the original strain the virulence was almost the same as that of “MB” strain.
Some of mice especially the young ones died of acute sepsis by M-type Var. at the early stage of infection, although secondary sepsis by “RT” were most prevalent in the later stage.
Exceptionally, sepsis by “GM” (Galactose M-tyye Var. of Ono) or“MT” (daughter type of M-type Var. of Murase) was also the cause of the death.
In most cases, M-type Var. and in few cases, “MT” or “RT” were found when the mice were sacrificed and cultued at the termination of the experiment.
It was assumed that the inoculated M-type Variant might contained some of“RT”or other in it as shown by the control experiment and at the same time “M”→“GM”, “M”→“MT” or “M”→“RT” Variation in animal body could not be neglected.
