TABLE OF CONTENTS 
NuMBER 1 (May 27, 1955) 
A New Narcotic Genus from the Amazon Slope of 
the Colombian Andes 
By Ricuarp Evans ScHULTES 
Pitch-yielding Trees of the Colombian Amazonia 
By Ricuarp Evans ScCHULTES 
A Note on the Genus Joannesia 
By Ricuarp Evans ScHULTES 
A New Generic Concept in the Euphorbiaceae 
By Ricuarp Evans ScHULTES 
Noumpser 2 (July 8, 1955 
Further Notes on American Orchids 
By Cuar.Les SCHWEINFURTH 
NumBeEr 8 (November 21, 1955) 
Plantae Colombianae XIII 
By RicHarp Evans SCHULTES 
NuMBER 4 (March 6, 1956) 
Estimates of Teosinte Introgression in Archaeolog- 
ical Maize 
By W. C. Gattnat, P. C. MANGELSDORF AND 
L. PIERSON . 
Number 5 (April 9, 1956) 
Archaeological Evidence on the Diffusion and Evo- 
lution of Maize in Northeastern Mexico 
By Pau C. MancetsporF, RicHarpD S. 
MacNEIsH AND Wat.ron C. GALINAT . 
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