353 



inicropyle in tlie latter stage form the egg-cell, s^iiergidae and 

 one of tlie polar nuclei. It was not possible to ascertain whether 

 the division of the group lying towards the chalaza lakes place in 

 the normal way, as the antipodal cells degenerate very early, per- 

 haps even during their formation. So much is certain, however, that 

 one or more antipodal cells and a lower polar-nucleus are always 

 formed, and the two polar nuclei speedily fuse together. 



The formation of pollen did not exhibit any special features in 

 the cases under examination, but very typical tetrads are formed 

 from the pollen-mother-cells. It was immediately seen, however, that 

 the pollengrains which were formed were largely sterile. No division 

 of the nucleus of a pollengrain was clearly observed, and artificial 

 cultures of pollen were unsuccessful, although a considerable quan- 

 tity of pollen was usually found on the ripe stigmas. From here 

 the pollentubes penetrated to any depth only in a very few stigmas. 

 In one single case did the pollentube reach the cavity of the ovule. 

 Although in this way the chance of fecundation was augmented 

 here, the ends of the pollentubes were not found in this embryosac 

 any more then in any of the other preparations. A male nucleus 

 was never in a single case to be found in this embryosac; the egg- 

 cell invariably remains lying alone and after some time begins to 

 enlarge of itself. Finally it begins to divide, after which the first 

 embryo- and suspensor-cells are formed. The further development 

 of the young embryo is quite normal. 



While this points to apogamy, it is only proved with absolute 

 certainty from the behaviour of the nuclei in the embryosac-mother- 

 cells. These commence to divide, like in so many other apogamous 

 plants, according to the heterotypical scheme. Many synapsis- and 

 spireme-stages are observed. Instead of real gemini of chromosomes 

 which totally or for the greater part fuse togetlier, merely pseudo- 

 diakinese-pairs are observed. The chromosomes approach each other, 

 but remain at some distance from each other. After this the division 

 has a homoiotypical character. Fig. 5 represents a telophase-stage 

 of the division of the embryo.sac-inother-cell of E. cocldeoides. In the 

 uppermost micropylar daughter-cell the chromosomes are present in 

 diploid number (12). The same number can also be counted in the 

 chalazal daughter-nucleus, though less distinctly. The knife of the 

 microtome had touched this nucleus, so that a few ends of chromo- 

 somes are to be found in the adjoining section. The figure shows 

 which fragments in the two cross-sections belong to each other. The 

 telophase-stage of E. confertifolia, which possesses vegetatively 24 

 chromosomes, is a still clearer and stronger proof of the apogamy, 



