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Pollen grains of several species and varieties ofNarcissus were examined with a light microscope and a scanning electron microscope. Normal pollen grains were kidney- or spindle-shaped with a germination furrow and a reticulate structure similar to that of the pollen grains ofAmaryllis.

Leaves of dark-grown corn ( Zea mays ) were illuminated for periods ranging from 3 minutes to 12 hours. The changes in the activities of ribose-5-phosphate isomerase, ribulose-5-phosphate kinase, and ribulose-1,5-diphosphate carboxylase were followed. The activity of ribose-5-phosphate isomerase did not change significantly until between 12 and 24 hours of illumination. An increase in ribulose-5-phosphate kinase activity occurred after a lag of about 6 hours. The increase in carboxylase activity began after 3 minutes of illumination and increased until after 3 to 6 hours in the light, after which it began to decline. The increases in these enzymes appear to be the result of protein synthesis.

Carbohydrate contents of both the photosynthetic and the storage organs of Narcissus tazetta L. were determined at four stages in their development under both 'natural' growing conditions and under conditions of varying light intensities. Starch was abundantly stored in all the storage organs, particularly in the bases of the photosynthetic organs under high light intensity and also at the second dor mant stage. However, its level remained relatively stable in the green part of the foliage leaf and the scape at different stages and appeared not to be affected by light except at very high intensity. It was found in both the bundle sheaths and guard cells. Sucrose, which is the first sugar of photosynthesis, was continuously exported from the green parts of the blade and the scape to their bases where it was also stored. In the dark the sucrose level became low in the green blade and the green scape but it rose with increase of light intensity. The hexose level was very low at the dormant stage in all organs examined but rose as they matured and exceeded that of sucrose in the green organs except in high light intensity. Hexose is formed presumably as a result of sucrose hydrolysis and is constantly lost, presumably through respiration. At senescence sugar disappeared almost completely from all the organs, while nearly 10 per cent of residual dry weight of starch remained in the dead tissues. The interrelationship between the carbohydrates and their movement in the leaf is discussed.

All the tissues in the contracted region of the contractile root of Narcissus become adjusted to the shortening of the root, which is brought about by vertical contraction and radial expansion of the inner cortical cells. Consequently the outer cortex including the exodermis is lifted passively in large wrinkles over the surface, while the vertical walls of cells in the stele become undulated or indented as in the case of the vessels. These phenomena are primarily brought about by the mechanical process of lifting and pulling due to the shortening and radial expansion of the inner cortical tissue. The possible mechanism of contraction of this cortical tissue is discussed.