522 



W. PEAESON ON" THE MOEPIIOLOGY OF 



becomes a tissue composed of very unequal cells (PL 32. fig. 23) as in Welwifschia *. Later, 

 the micropylar portion of the sac becomes filled witb an endosperm tissue resembling 

 that of the lower end. According to Lotsy, this occurs after fertilization. ^ The origin 

 of the upper part of the endosperm is at present not known with any certainty. Lotsy 

 states that " a greater or smaller number of the (unfertilized) nuclei of the fertHe part 

 of the embryo-sac surround themselves with a denser protoplasm, a membrane, and thus 

 form cells" t, and that these cells later become obhterated by the upward growth of 

 the primary endosperm tissue below it. There is reason to think that this account may 

 require some amendment. In any case, all but the apex of the sac— which usually 

 becomes disorganized in G. africanum after fertilization— is filled with an endosperm 

 tissue of a uniform character, and in the upper part of this the pro-embryos are 



embedded "'' 



+ 



D, SUMMAET OP EeSTJLTS. 



1. Gnelum G 



A. A fourth type of spike bearing male flowers and both incomplete and complete 



female flowers is described. The latter are pollinated. This is apparently a 

 spike which has been obscurely noticed by previous writers. 



B. The complete female flower of the androgynous spike occasionally possesses 



four envelopes. The fourth envelope is probably due to the duplication of the 

 middle envelope of the normal complete flower. 



C. In an ovule with four envelopes, the outermost bears an apparently axillary 



bud. 



D. Both the female and the pseudo-androgynous spikes frequently bear a smgle 



terminal ovule. 



E. As described by nearly all recent investigators, the envelopes of the incomplete 



female flower appear in acropetal succession. A swelling on the axis between 

 the insertions of the two integuments, considered by Lotsy to represent the 



aborted middle inteerument, is reco^uized 



w w.a_^vvJ-.. 1-, ^KJ ^^^^f^ 



P. The vascular supply of the pseud 



Dike resembles that already 



described for G. scandens. The capsule also resembles that of G. scandens m 



that it contains no mucilage cavity. 

 G. The male flower usually bears two anthers ; two supernumerary anthers are 



occasionally present. ^ . 



H. The antherophore arises by intercalary growth ; like that of JEphedra, it is 



probably a foliar structure representing two fused filaments. 

 I. The microspore mother-cell is four-chambered. 

 K. The pollen-grains in the micropyle contain either two or three free nuclei. 



Cf, 



X Coulter, 1908, fig. 7. 



t Lotsy, Z. c. pp. 97, 98. 



'/ 



containing well-developed endosperm but no cmhrvos." This is bo doubt correct. But ovules of the same 

 gathering, and probably in tbc same stage of development as tbose to wbicb she refers, contain numerous 

 pro-embryos which are easily mistaken for endosperm cells. 



