A dilute solution of iodine prevents the decomposition of hydrogen peroxide by colloidal platinum (G.
In the moist state of the thallus these colours are much less apparent, as the textures then become more or less translucent, and the thallus usually prevents the greenish colour of the gonidia (e.g.
It should be free from dirt - that is to say, free from clay or soft mud, for instance, which prevents the cement adhering to its particles, or again from sewage matter or any substance which will chemically destroy the matrix.
Enmann, who interprets the name as "she who prevents increase" (in contrast to Leto, who made women prolific), considers the main point of the myth to be Niobe's loss of her children.
This immunity is apparently not due to the absence of favourable conditions, but rather to the presence of some inimical factor which prevents the development of the parasite.