Analogues of Pyridoxine." (This lecture was illustrated by lantern slides.)Although inhibitors and poisons have been used for a long time in the study of isolated enzyme systems, it has been only in relatively recent years that physiological studies have been made with specific metabolite antagonists. Compounds with chemical structures similar to vitamins, hormones, and amino acids have been prepared which antagonize or inhibit such metabolites.' The term, antivitamin, has been applied to those compounds which counteract the function of vitamins. The inhibition ratio, or the ratio of antivitamin to vitamin that must be present for efficacy, is quite high for most antivitamins. Thus, in the case of pyrithiamine,* a thiamine antagonist, a ratio of approximately 40:l exists; that is, 40 moles of antivitamin are required to counteract the effect of 1 mole of the vitamin. Ott3 has recently reported that 2,4-dimethyl-3-hydroxy-5-hydroxymethylpyridine (desoxypyridoxine) possesses potent antipyridoxine activity in the chick. This compound has an inhibition ratio of 2:l and may therefore be considered the most potent of the vitamin B inhibitors yet discovered. Ott has also demonstrated4 that 2-methyl-3-hydroxy-4-methoxymethyl-5-hydroxymethylpyridine (methoxypyridoxine) is almost as potent an inhibitor of pyridoxine in chicks as is desoxypyridoxine. Methoxypyridoxine has been shown to possess pyridoxine activity in the rat, but no such activity has been observed with deso~ypyridoxine.~ Biochemical studies conducted by Porter, Clark, and Silbere reveal that pyridoxine-deficient rats treated with desoxypyridoxine and tryptophane excrete increased quantities of xanthurenic acid and kynurenine. Under comparable conditions, methoxypyridoxine effects a decreased excretion of these metabolic products.I n order to evaluate further the antipyridoxine activity of desoxy-This paper was presented by Doctor Mushett.

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as a third edition of that text because of certain changes in plan and emphasis. Like its predecessor, it aims to present the content of a general reference course, with, according to the preface, greater emphasis on non-book materials and more attention to reference practice. Although the changes in plan and emphasis are perhaps less extensive than the preface might seem to suggest, all appear highly advantageous, and examination indicates that the work fulfills its stated purpose admirably.An introductory chapter, "The Practice of Reference," treats very briefly the place of reference work in library organization, with definitions and explanations of the six component functions. The remaining chapters are concerned with reference materials, general and specialized, with emphasis on types. Some 554 basic titles are included, in contrast to 172 in the earlier work, though the latter listed 254 additional titles for general acquaintance. Each chapter contains a list of typical reference questions culled from the experience of reference librarians in various libraries-a feature sure to interest students. Almost every chapter concludes with a reading list, though unfortunately the items so listed are not included in the index. Dr. Shores' background comments on the history of specific titles or types should be of much interest to students since such information does much to humanize these keys to knowledge at which many are prone to look askance or to take for granted. The lucid and straightforward style, excellent format, pleasing and inviting pages, should do much to facilitate and encourage the reading of these meaty chapters.