Shame on Janusz Glowacki for practicing diagnostic medicine without a license in ''A Playwright Is Free (So Now What?)'' [March 4] by implying that rain triggers the autoimmune response in rheumatoid arthritis, thereby causing inflammation of the joints. Mr. Glowacki speaks of rheumatism, the British term for arthritis, which encompasses more than 100 diseases. Mr. Glowacki's ''elderly emigrant'' super ''twisted by rheumatism'' whose legs and hands are inflamed is, furthermore, ironically portrayed with a joyful smile on his face when it rains because of the scarcity of precipitation in his native Malta.
The predisposition to rheumatoid arthritis is probably a genetic marker on the sixth chromosome and the triggering agent is probably viral. With Mr. Glowacki's erroneous belief and profusion of egregious rheumatological innuendoes, we might as well return to the pseudoscientific superstitions espoused by Lavater, Gall and Mesmer. Physiognomy, phrenology or mesmerism, anyone?