CONIFERALES (TAXACEAE) 



327 



seeds (p. 43). All the other conifers ha\-e lost all traces of their 

 nucellar vascular systems. 



In Saxegothaea (149, 150, 152) there is a remarkable extension 

 of the tip of the nucellus, which protrudes beyond the micropyle 

 into an irregular, flaring apex, which is said to become covered by a 

 sticky secretion and to act as a stigma, continuing to grow for about 

 two months after pollination (tig. 379). This character appears, 

 in less degree, in Araucaria. 



Fig. 379. — Saxegothaea conspiaia: longitudinal section of ovule, showing the 

 stigma-like extension of the nucellus; X50. — After Noren (149). 



The development of the sporogenous tissue has been traced by 

 Strasburger (100) in Taxus, and it is presumably the same in the 

 other Taxaceae. The archesporium is a hypodermal plate, which 

 divides periclinally as usual. The outer cells, in connection with 

 the overlying epidermal cells, produce the large mass of sterile tissue 

 that caps the nucellus. Each primary sporogenous cell (mother 

 cell) is the innermost cell of a long row, and the number of 

 mother cells is approximately the same as the number of archesporial 

 cells (fig. 380). In most genera, apparently, these rows are not dis- 



