198 Maine Agricultural Experiment Station. 1920. 



growth tendency of the radicle in the normal direction. As a 

 result of this interaction between normal growth-tendency and 

 growth-inhibition the radicle takes its way in the direction of 

 least resistance. 



At germination in natural media in the soil, the factors ob- 

 taining in artificial germinators are not present and accordingly 

 the abnormal germination is either entirely absent or occurs only 

 to a very limited degree with some grasses. 



Likewise, the second consequence of the operation of con- 

 ditions prevailing in the germinator, i. e. the dying off of the 

 radicle within the glumes, either does not occur at all or only 

 very rarely at germination in the soil. 



The rupture of the tissues of the glumes is effected, as a 

 rule, by the coleorhiza. It accomplishes this chiefly by means 

 of its turgescence and may be assisted in this work by the short 

 and thick cells of its apical tissues. 



The chief function of the coleorhiza is its mechanical per- 

 formance in breaking through the tissues of the glume, it further 

 functions as a protective organ for the tender radicle and cares 

 by means of its hairs or trichomes for the fastening of the seed- 

 ling to the soil particles, thus assisting the radicle in its pene- 

 tration into the soil. 



The occurrence of the trichomes as observed in the course 

 of the investigation in a large number of grasses justifies the 

 conclusion that the formation of hairs is a general characteris- 

 tic of the coleorhiza of the Gramineae. 



The radicle emerges from the coleorhiza of grass-fruits 

 through a longitudinal, lateral opening formed by the cells being 

 detached and pushed apart without being injured in any way. 



Introduction. 



The anatomical and mechanical processes accompanying the 

 passage of the germinating embryo through the glumes of the 

 grass-fruits, especially of the true grasses, have hitherto been 

 given but little attention. Although the germination of the 

 Gramineae has long been studied with great interest, the chief 

 attention was centered on the cereals while the true grasses were 

 generally subordinated to them. 



