Teleutospores of heteroecious rusts never reinfect the host on which they are produced, so that in many cases the FIG.
20 (1906); Christman, "Sexual Reproduction of Rusts," Ann.
Iron, when exposed to moisture and air, "rusts"; but this process never takes place in the absence of air, and it is questionable whether it ever sets in in the absence of carbonic acid.
" Iron " (Liao), he said, " rusts, but gold always keeps its purity and colour, therefore my dynasty shall be called Kin."
Gymnosporangium sabinae, one of the rusts (Uredineae) passes one stage of its life-history on living pear leaves, forming large raised spots or patches which are at first yellow but soon become red and are visible on both faces; on the lower face of each patch is a group of cluster-cups or aecidia containing spores which escape when ripe.