A Study of the Life History of Trillium cernuum L.

Abstract

The following study of the origin and development of the female gametophyte of Trillium cernuum has been made with a view to a more detailed cytological and embryological study of T. cernuum and T. grandiflorum and their possible hybrids. It was undertaken at the suggestion of Dr. FERGUSON, to whom I am greatly indebted for helpful discussion and criticism. ATKINSON has given a careful description of microsporogenesis in T. grandiflorum. ERNST2 has published a very brief and as yet uncompleted account of chromosome reduction, development of the embryo sac, and fertilization in T. grandiflorum. GREGOIRE and WYGAERTS3 have used T. cernuum and T. grandiflorum as a basis for detailed studies on the reconstruction of the nucleus and the formation of chromosomes. As yet, however, no account of the life history of T. cernuum has been given. Trillium cernuum is a native of Massachusetts and grows in sufficient abundance in the vicinity of Wellesley College to furnish plenty of material for investigation. The work of collecting was done in i9ii and I9I2. From the first week in April until the end of May, material was gathered once or twice each day. The fixing was generally done in the field. The most satisfactory fixing agent was a weak solution of Flemming's chromo-acetic-osmic fluid. Of the several stains tried, Haidenhain's iron-alum-hematoxylin and Flemming's triple stain gave the best results.