Bot.— Vol. I.] CANNON— AVENA FATUA. 353 



IV. (a). The synergidae serve to nourish the young 



embryo. 



(b). The lumen of the embryo-sac begins to fill 

 first in the region of the embryo. 



(c). All but one or two layers of cells of the 

 nucellus are resorbed by the developing 

 embryo-sac. 



(d). The outer integument of the ovule is de- 

 stroyed ; the inner persists as the seed-coat. 



V. (a). The first two cell-walls (which mark off the 



proembryo) in the development of the 

 embryo appear in basipetal succession, and 

 show the three " Types" of Norner. 



(b) . The cotyledon and the stem-apex are derived 

 from the distal segment of the proembryo; 

 the root, the root-cap and the periblem 

 initials of the root from the middle seg- 

 ment; and the coleorhiza from the basal 

 segment. 



(c). The suspensor is separated from the embryo 

 by the fourth wall ; it does not subsequently 

 divide. 



(d). The primary tissues are cut off in the first and 

 second segments only; the divisions of the 

 third segment are very irregular. 



(e). The organs of the embryo originate in the 

 distichous manner characteristic of the 

 vegetative leaves of grasses. 



(f) . The scutellum appears to be analogous to the 

 haustoria of certain phanerogamic parasites. 



In conclusion I desire to express my gratitude to the offi- 

 cers of the botanical department, to Dr. D. H. Campbell in 

 particular, for helpful advice and encouragement to me 

 while pursuing the study of Avena. I ought to add also 

 that the work was nearly but not quite finished prior to Dr. 

 Campbell's departure for Europe in June. 



Stanford University, 



August 31, 1899. 



