1003 



to 50 feet high and 1| to 3 inches in diameter. Re- 

 ported to have a wide range in Africa. This species 

 has a very different appearance from the remainder of 

 the genus, but the structure of the spiculae in all 

 the species is very similar. For technical descrip- 

 tion see Colonel Munro ' s Monograph of the Bambusaceae, 

 in the Transactions of the Linnean Society, London, 

 Vol. 26, p. 127, 1870. 



Paulownia dudouxii Dode . (Scrophulariaceae . ) 42693. 

 Plants from Paris, France. Purchased from Messrs. 

 Vilmorin-Andrieux & Company. A recently Introduced 

 tree from Yunnan, China, differing from the common 

 Paulownia in its white flowers, slightly rosy, and 

 without spots. Flowers at the end of winter before 

 the leaves appear. 



Pavetta zimmermanniana Valet. (Rubiaceae.) 42767. 

 Seeds from Buitenzorg, Java. Presented by Dr. J. C. 

 Koningsberger , Director Botanic Gardens. A small 

 rubiaceous tree or shrub, with opposite, nearly ellip- 

 tic leaves and clusters of small, slender-tubed white 

 flowers. "The remarkable researches of Zimmerman and 

 Faber detailed in the Jahrbucher fur wissenschaf tliche 

 Botanik, vol. 51, p. 285, 1912, and vol. 54, p. 243, 

 1914, make this species of unusual interest. Faber 

 has proven that the leaves of this species of Pavetta 

 and of several others of this genus as well as of the 

 genus Psychotria and possibly other genera of the 

 Rubiaceae contain colonies of a nitrogen-fixing bac- 

 teria which he names Myco-bacterium rubiacearum . The bac- 

 teria of this species inhabit almost invariably the 

 micropyle of the young seed and when it germinates, 

 although not a motile form, grow through certain 

 stomata of the very young leaves and into the intra- 

 cellular spaces formed by the leaf tissues around these 

 stomata. Reacting one on. the other, there are formed 

 through the growth of the epidermis cells cavities 

 which later close entirely -and make bacterial knots 

 which are deeply imbedded in the leaf tissues. A single 

 leaf may have several dozen of these symbiotic bac- 

 terial knots. Faber was able by treating the seeds 

 with hot water and sublimate solution to kill the in- 

 habiting myco-bacteria and later infect part of the 

 seedlings grown from their seeds with pure cultures 

 of the bacterium. The artifically infected seedlings 

 grown in soil free from combined nitrogen grew well 

 and remained healthy for four months whereas those 



