



1917] WENIGER— EUPHORBIA f 267 



Sin 



locule. The inner integument 



while the outer integument grows beyond it. The megaspore 



subepidermal in origin 



ermis 



embryo sac, divide with great rapidity, producing a long, slender 



imbrj 



The embryo 



from 



megaspores. The syner 



the egg is 



esr^. 



situated between them. The pollen tube passes between the 

 synergids, and the fusion of the male nucleus with the egg nucleus 

 was observed. The fusion of the polar nuclei takes place near the 



e ephemeral and were seen by Miss 

 Lyon but once. The neck of the nucellus and the " glandular 

 hairs," as the cells of the obturator are called, disintegrate after the 

 entrance of the pollen tube, and the outer integument closes the 

 mouth of the micropyle. 



Hegelmaier (6) reports habitual polyembryony in E. dulcis. 

 From 2 to 9 embryos appear at the micropylar end of the sac. One 

 embryo, which comes from the egg and may be distinguished from 

 the others by the presence of a suspensor, develops into the single 

 embryo of the seed. Some of the supernumerary embryos come 

 from the nucellus. Two of them often reach the cotyledon stage, 

 with tissue systems differentiated; the other embryos appear as 

 irregular masses. Since the cyathium of this species has a very 

 small neck, Hegelmaier thinks it improbable that the flowers 

 are insect pollinated. Wind pollination is also improbable, because 

 of the regularity with which seeds are formed in the locules. In a 

 later paper Hegelmaier (7) admits that, although fertilization in 

 E. dulcis was not observed and although its possibility seems les- 

 sened by the sterility of a large proportion of the pollen grains, he 



occur. Fertilization is not necessary 



>rvn*; farm) rmrellar cells. There is a 



cannot 



em 



possibility that apogamy and also parthenogenesis occur. 



Roeper (17) reports observing 2 embryos in the seed of E. platy- 

 phylla. According to De Caxdolle (5), 2 embryos are also formed 

 in E. helioscopia. Schweiger (19) describes the obturator, nucellus, 



