Healing and fixing (治る/直す; 流る/流す).

I love getting e-mails in Japanese from 日本語の先生 and 習字の先生 because there's always something intriguing in the language, something I've never seen before or never noticed before. Several points of 日本語 interest in an e-mail I've just gotten from 習字の先生:

百日咳 hyakunichizeki, a "100 days' cough", whooping cough. The kanji are hyaku (100), nichi (sun or day), and seki (cough, with associated meanings of clearing throat &c.). Will have to look up 咳 in Henshall when I get home; there's kuchi 口 in the hen position that suggests mouth/throat, but I don't think I know that tsukuri.

流行　(ryuukou). Prevalent or in fashion. Kotoba includes at least one example with 行 read as ぎょう, as in the calligraphic style 行書 (gyousho) or the hen radical 行人べん (gyouninben), moving man. Kotoba actually says this compound is read as はやり (hayari). What really caught my attention about this is the first kanji—our old friend from ひばり美空さんの演歌, nagareru! Flowing, like the river of life in 川の流れ and the secret tears of the heart in 愛燦燦. Interesting that here we have another る/す pair, sort of, with the る form more self-motivated (flowing, as a river does) and the す form more external (draining, pouring, shedding, as in tears). But the る for also has れ. So, I guess,

涙を流す時、涙が流れる。
Namida o nagasu toki, namida ga nagareru.
When we shed tears, tears flow.
正しいかなぁ。

The IME fights me on these verbs, so my thinking may be wrong here.

治る and 直す. These have interested me for a while, with their similarity in sound and meaning. Naoru can mean healing (though apparently that can also be naosu), and naosu repair—note the similarity in kanji to 真, true/correct. And there seems to be some vacillation between two similar kanji for naosu, 直 and another that's similar but has a vertical and horizontal that form a corner in the lower left. 直 seems standard and pops up in the Windows IME as an option for both naoru and naosu; the Windows IME actually shows the "corner" kanji in the popup but then inserts it as the more standard symmetrical kanji. Saiga seems not to include the one with the corner; Kotoba has a common dictionary entry for 直す and 治す and uses the "corner" form for all senses of repairing or replacing. The -る / -す dichotomy seems to fit into the pattern of, eg, 渡る and 渡す, one (る) for action from the self and another (す) for action from outside. So, naoru, to heal (oneself); naosu, to heal/repair something else, with the deeper sense of replacing or reverting to a previous/original form. (Compare 元気 as healthy, with kanji meaning original/root and spirit.)