Structure, etc., of Epiphegus Virginiana. 391 



being flattened against each other (Fig. 17 h-i). In slightly 

 older anthers, these tetrads appear as four separate balled- 

 up nucleated masses of cytoplasm, lying in a clear shining 

 mucilaginous-looking mass. At this stage a great number 

 of disintegrating cells are lying around next the anther 

 wall, a degenerating tapetum probably. 



The mature pollen grain shows a double layer of clear 

 refractive thickening round its wall. Within is densely 

 stained protoplasm. It is invariably divided into two dis- 

 tinct masses, separated by a considerable space (Fig. 17 k). 

 One mass is very small relatively, and lies flattened against 

 the wall. It contains a small clear elliptical nucleus, with 

 a large dense nucleolus, and chromatin scattered along the 

 nuclear membrane. The larger protoplasmic mass shows 

 two slight lobings. A clear vacuole fills most of one lobe. 

 The other contains a large nucleus, spherical in outline, with 

 considerable chromatin and a large dense nucleolus. This 

 is probably to be regarded as the prothallial nucleus, while 

 the small flattened nucleus is the generative nucleus. 



Somewhat later, the pollen tube is seen emerging. The 

 spore wall looks thin and eaten away at one point, then a 

 bulging of the protoplasm occurs here. The tube pushes out 

 into the bulging here, the small nucleus lying against its side 

 wall. The large nucleus is seen remaining in the pollen cell, 

 and probably disintegrates there, as it is not observed later. 



The pollen tube grows across and enters the stigma, push- 

 ing its way between the cells and down the style. Two 

 nuclei now appear in it, undoubtedly resulting from a divi- 

 sion of the generative nucleus, and forming the two sperm 

 nuclei that are later noted in the macrospore cavity. 



Difficulties of Germination. 



It is surmised that for successful germination, the seed 

 of Epiphegus requires contiguity with the beech-root. The 

 seed falls upon the soil and is carried probably but a little 

 distance below the surface. At least this would be inferred 



