1 1 8 Smith oil Stnictiirc and Parasitism 



rather deeply-stained protoplasm, and large conspicuous nuclei. 

 In the middle of the nectary, these cells extend quite to the 

 bundle-ring, but on each side there is a rapid transition to the 

 parenchyma of the carpcllary walls. There is no special 

 covering of epidermal cells over the nectary (Plate XV, 

 Fig. 7). Externally, the gland appears as a small, rounded 

 whitish swelling at the base of the ovary. The presence of 

 this gland seems to have been overlooked by Chatin, for he 

 characterizes the genus as one in which the ovary is unaccom- 

 panied by an hypogjmous gland. 



Structure and Development of the Ovule and Seed. 



The mature seed, which is very small and light, is sur- 

 rounded by a tough, leathery coat, whose flattened cells have 

 thickened indurated walls. The seed itself consists of a mass 

 of endosperm cells, packed with starch, and enclosing a small 

 primitive embryo whose cells contain little or no starch. 

 The embryo is undifferentiated into plumule, cotyledons or 

 radicle. These seeds will not germinate in water, nor in a 

 nutrient solution made from the bruised roots of the host. 

 Koch states absolutely that the seeds of 0. speciosa, 0. rantosa^ 

 0. minor ^ 0. Hcdcrcs must come in contact with^the host-root 

 if they are to germinate, and Meehan finds the same for 

 Aphyllon. 



I have not yet worked out entirely the development of this 

 seed from the young ovule, and between Figs. 2 and 3 (Plate 

 XV), I have as yet no certain connecting links. Fig. i shows 

 the first appearance of the macrospore-mother-cell in veiy 

 young ovules. The ovule is here still orthotropous, and is a 

 small conical upgrowth, covered with one layer of cubical 

 cells and containing a large macrospore-mother-cell. Fig. 

 2, shows an older ovule. The ovule has here turned 

 through an angle of nearly 90 degrees. The macrospore- 

 mother-cell has greatly elongated, and is surrounded by 



