The account here presented is based entirely on the study of a white-spine variety of the cucumber, Cucumis sativus L., known as Burpee's No. 38I, Arlington. Seeds were obtained from the grower in I923 and I924. Abundant material for this study, and also for a cytological investigation, was secured from plants grown in the greenhouse at Purdue University in the autumn and winter of I923-I924. Additional material was grown in the botanical greenhouse at the University of Wisconsin in the summer and autumn of I924 and the spring of I925. A few plants were grown outdoors. Material was fixed in several fixing solutions. Schaffner's chrom-acetic and Flemming's medium chrom-osmo-acetic fixatives proved to be the most satisfactory. Whole staminate inflorescences of various ages were fixed, as well as individual staminate flowers. Inflorescences and individual flowers are very pubescent, and for this reason offer difficulty in fixation. An air pump was used to remove the air bubbles in the case of inflorescences and also of some individual flowers. Very satisfactory results were also secured by treating individual staminate flowers as follows: after severing a flower from the plant, it was placed under a dissecting lens, and there, with the use of a needle and scalpel, the hairs were removed from the whole perianth tube. A few scraping strokes of the scalpel easily accomplishes this. Then, after cutting off the pedicel very close to the base of the receptacle, and in most cases also removing the perianth at about the base of the calyx lobes, the clean-shaven portion was immersed in the fixing solution. In most cases sinking took place in a short time. The material was dehydrated, cleared in chloroform, and further treated according to the usual paraffin method. Sections were cut from 4 u to 25 ,u in thickness and stained in safranin and Delafield's haematoxylin, Flemming's triple stain, and Haidenhain's iron-alum haematoxylin. Some nearly mature staminate flowers were studied by hand dissection. [The Journal for April (I4: I69-226) was issued April 26, 1927.] 227