THE FEMALE GAMETOPHYTE 



91 



cated a lack of the usual definite organization, the male cells 

 being described as " wandering " in the cytoplasm of the sac 

 and fusing with one of several free nuclei which function as 

 eggs but have not organized into an egg-apparatus. This loose- 

 ness of organization in the cells of the embryo-sac has also been 

 observed by Karsten 115 in several species of Juglans, and he 

 emphasizes the resemblance to Gymnosperms, believing that 

 Angiosperms are derived from them, with such forms as 

 Gnelum as the point of origin. 



What may be called minor irregularities in the structure of 

 the female gametophyte have been described in a number of 

 forms. The reported occurrence of only one synergid in Orni- 



Fig. 40.— Helosis avyanensis. A, binucleate embryo-sac with antipodal nucleus already 

 disintegrating. B, later stage; micropylar nucleus has divided twice, giving rise to 

 two synergids, an egg (not shown), and the micropylar polar nucleus which gives 

 rise to the endosperm; no antipodals. (7, remains of synergids and egg; the 

 "pseudo-endosperm" nucleus dividing; no trace of antipodals. — After Chodat and 

 Bernard. es 



thogalum nutans, Santalum, Gompfirena, and Loranthus, has 

 long been known. In Loranthus Treub 13 savs that this is due 

 to the fact that the primary micropylar nucleus divides only 

 once, but it is also possible that the mother-nucleus of the 



