Cytological studies ofLathyrus sativushas been made. Mitosis has been studied with pre-treatment of root tips with 0.25% aqueous chloral hydrate solution for ½ hour and with 0.002 to 0.003 Mol. aqueous Oxyquinoline solution for 2 to 3 hours at 15°-18° C. The effect of the two treatments are similar, but in case of chloral hydrate the contraction is less severe. The 14 diploid chromosome can be classified into five different types each distinguishable from the other by its size, relative position of primary and secondary constrictions. There are two chromosomes with secondary constrictions and one with a satellite corresponding to those three nucleoli observed in first meiotic telophase and in the tetrad nucleus during formation of pollen grains. Behaviour of meiotic chromosomes is normal suggesting the diploid nature of the species.*