Of Ap]iyllo7i Unifloruin, Gray. 1 1 9 



a clearly-marked nucellus, while the primine has grown 

 nearly around the nucellus. Up to this stage there has 

 been clearly no formation of tapetal cells, and (although my 

 material was too badly shrunken to be very satisfactory) I have 

 reason to doubt their formation at any time. I have observed 

 many completely anatropous ovules, which contained within 

 the three cell layers one much elongated, darkly-staining 

 mass of protoplasm. Many of these showed two nuclei, but 

 a clear unmistakable transverse wall could not be observed. 

 Koch, in his " Entwicklungsgeschichte der Orobanchen," 

 figures for 0. spcciosa the division of the macrospore-mother- 

 cell into four, of which the upper one is the macrospore ; and 

 this division occurs when the ovule is turned half-way. If 

 the macrospore-mother-cell does divide in Apliyllon, the divi- 

 sions must occur at a much later period than they do in the 

 related species described by Koch. 



Plate XV, Fig. 3, shows a much older ovule. The integu- 

 ments fully surround the nucellus, and the outer one is closely 

 packed with starch, while the nucellus is pressed against by 

 the structures within. Owing to the lack of closely preced- 

 ing stages this ovule cannot be interpreted with complete cer- 

 tainty as yet. The probable interpretation, based upon the 

 development of related plants, is as follows : The multicellular 

 cell-body represents the mass of precociously developed 

 endosperm, which has grown up around the egg-cell into a 

 neck-like structure. The central cell is the egg, still unseg- 

 mented, and the long, plug-like body filling the apparent neck, 

 is the suspensor, consisting of two cells. At the opposite 

 end of the ovule, one cell represents the remnant of the 

 antipodal cells, which have become shrunken. Such forma- 

 tion of precocious endosperm is common throughout the 

 Orobancliaccte, and in Aphyllon it seems to take place to a 

 greater degree than in 0. spcciosa, as described by Koch, 

 where the neck-like upgrowth of the endosperm around the 

 suspensor is much less perfectly developed than in Aphyllon. 



