Morphology and Cytology of Guepinia Spathularia

SUMMARY 1. The mycelium of Guepinia Spathularia fills medullary rays and vessels of decaying wood, giving rise to fructifications at weak places where branches break through to the surface.2. Differentiation begins in the cortex. This is followed by the formation of a hymenium, and later, of a stalk. Finally, some changes take place in the appearance of the medulla. The hyphae are binucleate, but no clamp connections have been found.3. The young basidium is paraphysis-like, and binucleate. Its enlargement is inaugurated by the fusion of the primary nuclei.4. Two divisions of the fusion nucleus give four nuclei, longitudinally arranged in the basidium. The first of these divisions is regarded as the reduction division, but the chromosome number was not determined.5. Two nuclei pass into each epibasidium, but only one passes into each spore. The other remains in the epibasidium, there degenerating.6. The spores are uninucleate at discharge, but the nucleus soon divides and a septum is laid down, making the mature spore two-celled.The work was done in the mycological laboratory of the State University of Iowa, under the direction of Professor G. W. Martin. Photomicrographs were made by Mr. Travis W. Brasfield.