“…Detailed investigations carried out in surgical and infants' wards on the effects of the introduction of single hygienic measures have been published (Knorr & Wallner, 1957;Ravenholt, Wright & Multhern, 1957;Gillespie, Simpson & Tozer, 1958;Felton, Willard & Bass, 1959;Frappier-Davignon, Frappier & St-Pierre, 1959;Myers, Nimeck & MacKenzie, 1959;Plueckhahn, 1961;Caplan, 1962). Naturally, the scope of such investigations must be limited.…”