CONIFERALES (PINACEAE) 269 



this is a feature of the Cupressineae, its occurrence among the Taxo- 

 dineae has tempted various investigators to use it as a reason for 

 transferring certain genera of that tribe to the Taxodineae. The 

 two tribes are confessedly artificial, but such a character is not a safe 

 one, for the grouping of archegonia is often indefinite and variable. 

 This complex has been found in Sequoia (50, 64), Taxodium (76), 

 Cryptomeria (93), and Cunninghamia (147, 180), but it does not 

 occur in Sciadopitys (175). Both species of Sequoia show an inter- 

 esting transition between separate archegonia and an archegonial 

 complex, the numerous archegonia occurring singly or in groups. In 

 the three other genera observed there is sometimes a layer of endo- 

 sperm cells between adjacent archegonia; and in Cunninghamia 

 (r47, 180) the group of archegonia (15 in the preparation figured by 

 Miyake) surrounds a central mass of endosperm tissue. Among 

 gymnosperms there seems to be a sequence in the distribution of 

 archegonia, the most primitive situation being numerous scattered 

 archegonia, followed by fewer archegonia derived from superficial 

 cells of the micropylar region, and then by their organization into a 

 complex. In none of the Taxodineae has a ventral canal cell been 

 discovered, but in all of them a ventral nucleus is cut off, which is 

 sometimes very ephemeral. 



Among the Cupressineae the number of archegonia ranges from 

 five to about one hundred, the number in Thuja (72) averaging six, 

 in Juniperus communis (173) ranging from four to ten in a single 

 complex, in Libocedrus (131) ranging from six to twenty- four in the 

 complex, and in Widdringtonia (159, 176) ranging from thirty to 

 one hundred. The neck cells appear to be always in a single tier, and 

 vary in number between two and eight, the number for Juniperus (132) 

 and Widdringtonia (176) being usually four, and Thuja (72) ranging 

 from two to six. In Thuja the neck cells begin to disorganize as 

 soon as they are formed, and are almost completely absorbed by 

 the enlarging central cell (figs. 299, 300). In the whole tribe the 

 archegonial complex is a feature, being compactly organized, with 

 a distinct and common jacket and a common chamber. No ventral 

 canal cell is formed, but the ventral nucleus is always cut off, as 

 among the Taxodineae. The case of Widdringtonia (i 59, 1 76) deserves 

 special mention, and it seems to be duplicated in Callitris. Before 



