THE FEMALE GAMETOPHYTE 



101 



of Casuarina, but in this latter 

 instance they are derived from 

 mother-cells. Other Archichlam- 

 ydeae with active antipodals are 

 Hecheria (Johnson 114 ), in which 

 they are sometimes six to eight in 

 number; Asarum (Hofmeister 2 ), 

 in which they are very long, ex- 

 tending at fertilization from one- 

 third to one-half the length of the 

 embryo-sac, and sometimes divi- 

 ding; Jejfersonia diphylla (An- 

 drews 37 ), in which they become 

 about one-half as long as the 

 embryo-sac ; Eriobotrya ( Guig- 

 nard ! -j, in which they are large; 

 and Anoda (Guignard 12 ), in 

 which they are prominent and 

 often binucleate. 



Among the Sympetalae the 

 Compositae are especially note- 

 worthy for the extensive develop- 

 ment of the antipodal region (Fig. 

 47). In this family the chalazal 

 end of the elongated sac is very 

 narrow and the antipodals are 

 superposed. In a number of 

 cases, as in Doronicum, Petasites, 

 and Taraxacum, there are usually 

 only three antipodals, but they 

 remain active ; while in Tussila- 

 go (Guignard 12 ) there are usual- 

 ly four; in Senecio (Mottier 20 ) 

 two to six; in Silphium (Mer- 

 rell 77 ) three to eight; in Conyza 

 (Guignard 12 ) eight to ten; in 

 Aster novae-angliae (Chamber- 

 lain 35 ) three to thirteen; and in 

 Antmnaria (Juel 57 ) they con- 

 tinue to divide until quite a tis- 



Fig. 48. — A, Sherardia arvensis. Em- 

 bryo-sac before fertilization ; low- 

 er antipodal acting as an hausto- 

 riurn. B, Callipeltis cucullaria, 

 showing lower antipodal still act- 

 ive after embryo and endosperm 

 are considerably advanced.— After 

 Lloyd. 105 



