Behind front-line polio treatment facilities lies a two-way research program now under way at the Institute of Microbiology and Hygiene at Montreal and at Toronto's Connaught Medical Research Laboratories. Here, backed by an $83,000 federal research grant, studies of polio virus, and its cultivation in tissue culture, are being made, aimed at further developing and perfecting a vaccine for the prevention of this crippling disease. And at the Connaught Labs, technicians are producing quantities of the Salk vaccine which this year will be given extensive trials throughout Canada. These trials, which will see an estimated 500,000 Canadian school children vaccinated, will be arranged and conducted by provincial health departments. Up to $375,000 of national health grant funds, to be matched by an equal amount from the provinces, have been earmarked to ensure an adequate supply of the Salk vaccine for the trials.