Changes in Acid and Alkali Tolerance with Agf’, in Planarians with a Note on Catalase Content

During a study of the effect,s of certain typical acids, bases and salts upon living planarians (Planaria dorotocephala, P. maculata and P. veEata), observations were made which are here reported on account of the wider interest of their bearing upon tolerance of H+ and OHions, upon the relative efficiency of the mechanism for regulation of neutrality in young and old individuals, and upon the problem of acidosis in general. Methods. A closely graded series of concentration of the acids (hydrochloric chiefly, also sulfuric and acetic) or alkali (sodium hydroxide) is made up from standardized N or 0.1 N solutions by dilution with aerated well water or other (Lake Michigan or Lake Ontario) water in which the worms live and thrive. The well water, which was used chiefly, has a pH value of 7.5 to 7.6 and an ion and gas content to be published with the larger study above mentioned. Both disGlled water and strongly chlorinated tap-water are in themselves injurious to these worms and hence could not well be used for the purposes of these experiments; but similar tests are now being made with P. maculata in distilled water, this species being but little affected by dist,illed water in the period of time required. Into the series of dilutions of an acid or alkali in 500 cc. or 1000 cc. Erlenmeyer flasks, filled and ready to be plugged with rubber stoppers, are introduced the flatworms, usually ten larger (18 to 20 mm.) and ten smaller (8 to 12 mm.) specimens together, all selected sound from established well-fed cultures. In some cases a similar group of three easily distinguishable sizes was used (22& mm., 15rt mm. and 8=t mm.). In control flasks all such individuals live practically indefinitely.