The Prothallia of Aneimia and Lygodium

SPORE COATS The spores of Aneimia and of Lygodium have three distinct coats. The exine is formed first, and as it broadens its composition changes from cellulose, so that with safranin it stains red, and then red and yellow. The change may be from cellulose to suberin, which stains red, and then to suberin and pectin, as pectin stains yellow. The exine of Aneimia hirsuta has ridges on the outer surface. The intine is the second coat formed, and is the one which covers the filament when it emerges from the spore. It remains a delicate cellulose wall. The epispore is the last to form, and in both Aneimia and Lygodium is produced by the activity of the tapetal protoplasm. In Lygodium granules appear in the protoplasm, increase in size, and adhere to the exine. In Aneimia hirsuta spines are formed on the ridges of the exine. The protoplasm forms a thin sheet over these projections and over the intervening surface of the exine. DEVELOPMENT OF THE THALLUS The first wall of the spore does not separate the rhizoid and first prothallial cell, but the spore contents divide into two cells of unequal size, from the smaller of which the rhizoid is produced. The apical cell of Lygodium is terminal, appears early, and is remarkably persistent. In Aneimia it appears later and is lateral. The lobes of the heart-shaped thallus are at first unequal. In Aneimia hirsuta this inequality is permanent, but in Aneimia Phyllitidis and in Lygodium the lobes become later of the same size. SEX ORGANS The general course of development in both antheridia and archegonia does not differ from that in the Polypodiaceae. The first wall of the antheridium is not, as reported, always flat, but may be so concave as to touch the basal wall. The number of sperms is large. The archegonia have two neck canal nuclei.