Germination of Grass-Fruits. 199 



The presence of flowering glumes and — in certain species — 

 sterile glumes enclosing the caryopsis, the development of long 

 and thick trichomes on the coleorhiza of grass-fruits as compared 

 with the short and scant hairs on the coleorhiza of cereals, the 

 sending out, at the beginning of germination, of the main radicle 

 alone instead of several rootlets as in the case of the germinating 

 caryopsis of cereals, and finally the various types of abnormal 

 germination reported in this paper, are all features peculiar to 

 the true grasses and interesting enough to warrant a separate 

 consideration of the germination of grass-fruits. 



The present account is an attempt to follow the germinating 

 embryo of the hulled grass- fruits on its way through the sur- 

 rounding tissues, and to record the anatomical changes and 

 mechanical processes accompanying germination. 



The changes in the anatomy of the pericarp caused by the 

 germinating embryo have not been examined in this study. 



The material for this investigation comprises chiefly the 

 economically important grasses. In the course of this study 

 over 18,000 seedlings were examined. The illustrations, some 

 of them hand drawings from nature, were all made by the 

 writer. 



I. Normal Germination of Grass-Fruits. 



I. THE PENETRATION OF THE COLEORHIZA THROUGH THE 

 PERICARP. 



The first stages of the process of germination of the hulled 

 grass-fruits take place in a manner similar to the general type of 

 the Gramineae. Germination begins with the absorption of 

 water. The germ becomes turgescent and lies now close to the 

 pericarp. Contrary to the germination of the Cyperaceae and 

 some other monocotyledonous plants the first symptoms of 

 growth are normally visible at the base of the embryo. First 

 the coleorhiza extends and strikes upon the pericarp. No record 

 is available of the anatomical changes in the pericarpial tissues 

 caused by the breaking through of the coleorhiza. Nor are the 

 macroscopic descriptions of this stage in the germination con- 

 cordant. 



