178 TORREYA 



Mr. Robert Hulbary, the second speaker, discussed "Three Dimensional Cell Shapes 



in the Differentiating Cortex of Elodea Stems." 



There were three purposes for making this study ; one to determine the three 

 dimensional shapes of the mature cortical cells in the presence of large air spaces, 

 another to investigate the shapes of the cells in the apical meristem, and a third to 

 study changes in shape as the cortical cells differentiate. 



In the cortex of Elodea (Anacharis dcnsa \'ictorin) the three-dimensional shapes 

 of the cells in the stem cortex are influenced b}- the presence of large internodal 

 lacunae. The cortical cells are elongated parallel to the long axis of the stem, 

 and they contain chloroplasts and starch grains. One hundred cells from each of 27 

 consecutive internodes were studied to determine the number of faces per cell. Then 

 600 additional cells — 100 from each fifth internode — were studied more intensively 

 for number and kinds of faces and the combinations of faces. The average number 

 of faces per cell for the 3300 cells was 8.79. More than one third of all the cells 

 (1443) were 8-hedra. Quadrilateral faces occurred more frequently than all of the 

 other kinds added together. In 600 cells studied more intensively only 31 different 

 combinations of faces were encountered. This apparent uniformity in cell shape in 

 Elodea stem cortex is further attested to by the fact that three of these 31 patterns 

 were outstandingly characteristic for the issue. 



Using the method of Duchartre, the average number of faces per cell in the apical 

 meristem was found to be 13.88. 



The large internodal air canals originate schizogenously, and they are completely 

 delimited at the base of the apical meristematic region. The reduction in number of 

 faces per cell from the apical meristem to the mature cortex and the other dift'erenti- 

 ations in cell shape concomitant with the development of the internodal lacunae are 

 due to the cell enlargement and to cell divisions which are limited to two distinct 

 planes. 



Following discussion of the two talks, the meeting was adjourned at 4:55 p.m. Tea and 



refreshments were then served by friends at the Garden. 



hoxor m. hollixghurst, 

 Recording Secretary. 



Addition's to the List of Botanists ix the Froxtispiece 



No. 24. For C. F. Mook read P. V. Mook 



No. 47. Mrs. George S. Powell 



No. 48. George S. Powell 



No. 49. Mrs. Robert Hagelstein 



Dates of Publicatiox of Torreya, Volume 43 



Number 1. July August 27, 1943 



Number 2. December February 10, 1944 



