This book is a translation of those parts of Schleicher's 'compendium der vergleichenden Grammatik der Indo germanischen sprachen' Which treat directly of the indo-european original language, Sanskrit, Greek, and Latin: it was undertaken for the use of students of Greek and Latin Philology, on the suggestion of Mr. Peile, m.a., of Christ's, College, Cambridge, to Whom I am indebted for several hints and corrections. My thanks are due to Herr Gustav Voigt also, for help kindly given.