Goodmsuaun (1955) ansd Gray et al.(1957) inuuph-eating the iushihitionu of earhousic anuhuydlrase, particularly that its brains, ins tlso’amsticonsvulsanst action of emorbouuie anlsv (lraso’inslsii) itors. Austi-consvulsanuts of tisis class tore imsvaluable tools for investigatiusg tIne phsysiology of experitsuenutal s (’izures. Pertinemst to tue questions of the usuecisanisusu of action at thue phsysiologieal level, it was thought to be of interest to comsupare tue antieonsvulsant(‘feet associated withs carbonuio’ansisydrase inuisibitiois to that of diphensylisydanstoits and to look for possil) le qualitative dif-ferences. 1) iphuensvlhuvdaustoins huas been stated to Isave no effect on ctorbonuie atshsvdrase in tint’l) rainS of msuiee (Milhielsap, Woodhury ausd Golodmans, 1955). Methsazolamuuide was choseuu over acetazohamsuide because it gives a nuueiu lsiglner eotscentratiotu of carbotsie anisydrase inlsil) itor ins mouse bunts thans amu equal (lose of thue latter (Gray et al, 1957); it is also to uuuoro’p (Itenst ansticonsvulsauut agent iuu rats auuol nsiee. The struetunral formuuula of usuethsazolamsside, svnsthnesized by Youmsg ci a!.(1956), has beets Shuolwts its a previous eotssuuuunsicatious (Grtov et a!., 1957).

1IETHol) s. Royal Hart nutihe albinso rtots, 120 to 150 g, tond ahbiuso Mansor Ftormsu male mice, 18 to 24 g, were umsed ins all experinuensts except wisere indicated. They had beens ins the laboratory onne This work hsas beens reported ins part inn Fed.