ACACIA SEEDLINGS. 93 



and plurinerves, but the evidence to hand points to the 

 uninerves as being the earlier form. 

 Twin Stems. 

 A curious feature noticed in connection with seedlings of 

 A. juniperina raised from seed obtained near Professor 

 David's residence at Woodford, is that in two separate 

 cases one seed produced a divided hypocotyl, each portion 

 becoming a separate stem having its pair of cotyledons, its 

 one pinnate leaf, bipinnate leaves and phyllodes. (See 

 Plate VIII, Nos. 3 and 4). In the case of Number 3 the 

 bifurcation occurs just below the cotyledons, one of which 

 is slightly higher than the other, but in Number 4, although 

 the division first appeared at about the same position, it 

 gradually worked down as the plant grew, until it reached 

 the base of the hypocotyl. This appears to be the first 

 record of twinning in the genus Acacia. 



Mr. E. O. Andrews has recently found an example of 

 twinning in a seedling near Botany Bay, apparently A. 

 juniperina, and extended investigation will probably show 

 that the feature occurs in many species. 



Transport of Seeds by Water. 

 In connection with plant distribution over isolated areas, 

 and the possibility of certain species being indigenous to a 

 particular country or not, the question of transport of seeds 

 by water has been much discussed by various writers. 

 Where a species is found in two or more continents or on 

 widely separated islands, theories are propounded to 

 account for its distribution over these areas. Two of the 

 commonest theories in regard to such dispersal are that the 

 distribution is due either to a former land connection having 

 existed between the two countries in question, or that 

 seeds may have been transported by water. In certain 

 cases the question of dispersal by wind and birds has to be 

 carefully considered. The only Australian species of 



