THE MEGASPORANG1UM 



61 



groups. Fischer 15 describes a several-celled archesporium in 

 Helianthemum, Guignard 1T an occasional two-celled archespo- 

 rium in Capsella, and Treub 18 a two-celled archesporium in 

 Loranthus and one of four or five cells in Viscum, while it has 

 long been known that Thesium has a several-celled archespo- 

 rium. More to the point, however, is the occurrence of a several- 

 celled archesporium among the Asclepiadaceae (Frye 66 ), the 

 Kubiaceae (Lloyd 45 ' 61 ) (Fig. 23), and the Compositae. In the 

 latter family Ward 14 describes an occasional archesporium of 

 three cells in Pyrethrum balsaminatum, Mottier 26 found an 

 occasional two-celled archesporium in Senecio aureus, and the 



FIG. 25. Ranunculus septentrionalis. Longitudinal sections of nucellus, x 400. A, 

 eight-celled archesporium. , later stage showing germinating megaspores with 

 two and four nuclei. After COULTER.** 



several-celled archesporium of Chrysanthemum Leucanthemum_ 

 is \vell known. 



It is somewhat remarkable that among the Monocotyledons 

 there is no record of an archesporium of more than one cell 

 except in the case of Ornithogalum pyrenqicum, which Guig- 

 nard 17 reports to have an archesporium of two cells, only 

 one of which gets beyond the archesporial stage; and the pos- 

 sible case of Lilium candidum, in which Bernard 51 reports two 

 embryo-sacs. We have also seen two preparations of L. phila- 

 delphicum, one showing three archesporial cells and the other 

 five. 



