THE FEMALE GAMETOPHYTE 



89 



and Paphiopedilum insigne (Afzelius, 1916) it has been noted that 

 sometimes the two chalazal spindles of the last division come to 

 lie more or less parallel and very close to each other and eventually 

 coalesce to form a single large spindle which produces 2 diploid 

 nuclei instead of the 4 haploid ones which would have been formed 



B C 



Fig. 57. Embryo sacs with fewer or more than eight nuclei. A, Elatine triandra, 

 six-nucleate embryo sac which has arisen by omission of last division at chalazal 

 end; the two black masses represent degenerated synergids. B, E. hydropiper, 

 fusion of two eight-nucleate embryo sacs, resulting in 16-nucleate compound embryo 

 sac. (After Frisendahl, 1927.) C, Sandoricum koetjape, embryo sac containing 

 cytoplasmic vesicle with several nuclei. (After Juliano, 1934-) 



in the ordinary way. This results in a 6-nucleate embryo sac with 

 a haploid micropylar quartet, a diploid lower polar nucleus, and a 

 single diploid antipodal cell (Fig. 58). 



The reverse condition, i.e., the occurrence of more than 8 nuclei 

 in the embryo sac, is less frequent and may arise in three ways: 

 (1) fusion of two embryo sacs (2) migration of the nuclei of nucellar 

 cells into the embryo sac ; and (3) occurrence of secondary divisions 

 of some of the first-formed 8 nuclei. 



