CONTENTS 



Thompson, W. Oilman. Address of welcome i 



MacDougal, D. T. The mechanism and conditions of growth 

 (with plate i) 5 



Thompson, W. P., and Bailey, I. W. Are Tetracentron, Trocho- 

 dendron, and Drimys specialized or primitive types? (with 

 plates 2-4) 27 



Chivers, Arthur H. Directing factors in the teaching of botany. . 33 



Barnhart, John Hendley. Segregation of genera in Lentibu- 

 lafiaceae 39 



Call, Richard Ellsworth, Observations on the flora of Mam- 

 moth Cave, Kentucky 65 



Yampolsky, Cecil. Observations on inheritance of sex-ratios in 

 Mercurialis annua 69 



Humphreys, Edwin W. Triassic plants from Sonora, Mexico, in- 

 cluding a Neocalamites not previously reported from North 

 America (with plate 5) 75 



Taylor, Norman. A white-cedar swamp at Merrick, Long Island, 

 and its significance (with plates 6-10) 79 



Blakeslee, Albert F. Inheritable variations in the yellow daisy 

 {Rudheckia hirta) 89 



Harper, R. A. On the nature of types in Pediastrum 91 



Howe, Marshall Avery, and Hoyt, William Dana. Notes on 

 some marine algae from the vicinity of Beaufort, North Carolina 

 (with plates 1 1-15) 105 



Levine, Michael. Somatic and reduction divisions in certain 

 species of Drosera (with plates 16-19) 125 



Shaw, Harry B. Self, close and cross fertilization of beets (with 

 plate 20) 149 



Gager, C. Stuart. Present status of the problem of the effect of 

 radium rays on plant life 153 



SiNNOTT, Edmund W. Endemism as a criterion of antiquity among 

 plants 161 



Graves, A-rthur H. A botanical trip to North Wales in June 167 



Orton, C. R. North American species of Allodus 173 



Atkinson, Geo. F. The development of Lepiota cristata and 

 L. seminuda (with plates 21-26) . 209 



Harris, J. Arthur. A tetracotyledonous race of Phaseolus vulgaris. 22() 



vii 



