94 



MORPHOLOGY OF ANGIOSPERMS 



may be said that these eggs appear earlier in the history of the 

 gametophyte than is possible for archegonia, which are rela- 

 tively late structures. 



The character and behavior of the egg will be discussed 

 under fertilization, but the synergids present certain peculiari- 

 ties that may be considered here. The name " synergid," given 



by Strasburger, has proved most ap- 

 propriate, for it is usually both a nu- 

 tritive and mechanical " helper " in 

 the process of fertilization, although 

 it does not " serve to convey the fer- 

 tilizing substance from the pollen- 

 tube to the oosphere," as once sup- 

 posed. The two synergids follow the 

 configuration of the apex of the sac, 

 which is usually rounded, and hence 

 they are pyriform for the most part. 

 In certain cases, however, the sac be- 

 comes pointed or even much elon- 

 gated, and the synergids develop 

 beak-like extensions of more or less 

 prominence, which in many cases 

 have been found to pierce the wall of the embryo-sac and 

 extend into the micropyle (Fig. 44). Occasionally the beaks 

 show delicate longitudinal striations, and were called by Schacht 

 the " filiform apparatus." Such beak-like extensions of the 

 sac and synergids are usually associated with narrow and long 

 micropyles, and doubtless are of assistance in the progress of 

 the pollen-tube. Among the Monocotyledons they are by no 

 means so common as among Dicotyledons, but are well scat- 

 tered among the families. For example, they occur in Sorghum 

 and Zea (Guignard 71 ), Eichhornia (Smith 53 ), Crocus (Hof- 

 meister *), Romulea (Ferraris 12 °), and Gymnadenia (Marshall- 

 Ward 7 ), and doubtless in others. Among the Archiehlamy^e 

 they are more numerous, having been noted in Salix (Chamber- 

 lain 40 ), Quercus (Conrad 78 ), Santalum, Polygonum (Strasbur- 

 ger 5 ), Hepatica (Mottier 3fl ), Thalictrum (Overton no ), Silene 

 and Capsella (Guignard 12 ), and becoming very long in Euphor- 

 bia (Miss Lyon 54 ) and Slum. They are even more common 

 among the Sympetalae, a fact perhaps to be associated with the 



Fig. 43. — Polygonum divarica- 

 tum. Embryo-sac ready for 

 fertilization : showing syner- 

 gids with " filiform appara- 

 tus," egg, and primary endo- 

 sperm nucleus ; x 540. — After 

 Strasburger. 6 



