ever, and is orly surrounded by the outer integument, so 

 that it lies in the endostomium (fig. 3, 6, 14); the strong 

 longitudinal growth of the inner integument is chiefly 

 directed downwards. At its base, near the chalaza, it of 

 course remains connected with the nucellar tissue. 



Now it is very remarkable, that the nucellar tissue 

 does not participate by cell division in this strong longitu- 

 dinal growth of the ovule. The portion of the nucellus, 

 which projects beyond the inner integument, remains 

 unaltered, except for certain changes, which the spore 

 mother-cell undergoes, and which will be discussed below. 

 We may however at once point out, that in the formation 

 of embryo-sac and egg-cell, the whole apparatus remains 

 in the same place, and is therefore never surrounded by 

 the inner integument. 



The portion of the nucellus lying below this, is now 

 elongated by the extrême stretching of a single cell (or 

 in some cases perhaps two cells) in the central and in 

 each of the 5, 6 or 7 pcripheral rows of cells, of which 

 it consists (fig. G). The nuclei often also assume an extcn- 

 ded shape, so that one gets the impression that a passive 

 stretching has taken place. At the same time a digestion 

 of the longitudinal walls occurs, and fînally the protoplasts 

 also coalesce more or less. In this way a great cavity 

 arises, containing protoplasm, often in a peripheral layer 

 and with 6, 7 or 8 nuclei (fig. 12, 14), perhaps sometimes 

 even more in conséquence of nuclear fragmentation, 

 which seems to occur. 



If an ovule is examined in this stage, without the history 

 of its development having been traced, this cavity is ine- 

 vitably regarded as the embryo-sac, and the real embryo- 

 sac, which lies above it, is then taken for the egg-appa- 

 ratus. It is in this way that Warming, who, for want of 

 the necessary material could only trace part of the deve- 



