This journal provides immediate access to some articles. Volume 7(6); June 1921 Astronomy The Angular Diameter of Alpha Bootis by the Interferometer PMCID: PMC1084820 Changes Observed in the Crab Nebula in Taurus PMCID: PMC1084821 Biology Note on Moving Equilibra PMCID: PMC1084818 Genetics Variation and Inheritance in Size in Trypanosoma Lewisi: II. The Effects of Growing “Pure Lines” in Different Vertebrate and Invertebrate Hosts and a Study of Size and Variation in Infections Occurring in Nature PMCID: PMC1084817 Mathematics A Formula for the Vicosity of Liquids PMCID: PMC1084819 Physiology Feeding Experiments with Mixtures of Foodstuffs in Unusual Proportions PMCID: PMC1084816 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||