294 PLANT LIFE. 



tions ( c 314) which are homologous with those known to arise 

 from the fertilized egg and adja< ent parts. In all these cases 

 the fructification may be considered the homologue of the 

 sporophyte of higher plants, for, even though its origin is 

 now purely vegetative, this has come about by reduction from 

 more perfect ancestors. 



397. Apogamy. — In certain of the higher plants sexual re- 

 production is sometimes replaced by a process of budding, 

 which differs from reproduction by brood buds ( c 361 ff . ) 

 in giving rise to the other phase from that on \vhi< h the bud 

 arises. Some ferns, for example, regularly produce upon the 

 gametophyte a bud which grows into a sporophyte, the sex- 

 organs being functionless. This process is called apogamy. 



398. Polyembryony. — Among the seed-plants a budding 

 of the megasporangium, instead of the fertilization of the egg, 

 ma}- produce an embryo. Except that the embryo so pro- 

 duced suspends its growth and becomes a part of a seed, such 

 reproduction is in no way different from that by brood buds 

 (^[ 361 ff.) It is common in the orange, and often results in 

 the formation of more than one embryo in the seed. 



Results of sexual union. 



The immediate result of the coalescence of a male and a 

 female gamete is the formation of a cell capable of producing 

 a new plant, i.e . a spore. The first step toward this is the 

 formation of a wall about the spore. It may then grow at 

 once into a new plant, or it may remain dormant for a longer 

 or shorter time. 



399. Resting spores. — In the latter case it is called a 

 "resting spore." To protect itself, it thickens its-wall, often 

 very greatly. It may then escape from the parent by the 

 breaking of the ovary in which it lies, but more commonly it 

 remains enclosed until set free by the death of the parent 



