﻿A STUDY OF THE LIFE HISTORY OF TRILLIUM 

 CERNUUM L. 



Margaret Heatley 

 (WITH PLATE XXVIl) 



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 1 has given a careful description of microsporo- 

 genesis in T. grandiflorum. Ernst 2 has published a very brief 

 and as yet uncompleted account of chromosome reduction, develop- 

 ment of the embryo sac, and fertilization in T. grandiflorum. 

 Gregoire and Wygaerts 3 have used T. cernuum and T. grandi- 

 florum 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 191 1 and 1912. From the first week in April until the end 

 of May, material was gathered once or twice each day. The hxing 

 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. 



