SIZE VARIATION IN TRACHEARY CELLS: 



I. A COMPARISON BETWEEN THE SECONDARY XYLEMS 



OF VASCULAR CRYPTOGAMS, GYMNOSPERMS 



AND ANGIOSPERMS.i 



By I. W. Bailey and W. W. Tupper. 



Received, February 10, 1918. 



Introduction. 



In the study of cell size in plants and animals, much emphasis is 

 placed, during the last thirty years, upon the relations between cell 

 size and body size, organ size and nuclear size. Sachs (1893) calls 

 attention to the fact that, although plants and animals vary enorm- 

 ously (0.001 mm. to 100 m.) in their linear dimensions, there is not 

 a proportional variation (0.001 to 0.05 mm.) in the size of their cells. 

 He formulates (p. 73) the generalization that "zwischen der Grosse 

 der Organe und der ihrer Zellen keinerlei Proportionalitat besteht; 

 die Grosse der Organe, zumal homologer Organe, steht vielmehr mit 

 der Zahl der Zellen im Verhaltniss." His assistant Amelung (1893) 

 reaches a similar conclusion (p. 187): "Dass namlich bei morpholo- 

 gisch gleichen Pflanzentheilen trotz der ausserordentlichen Grdssen- 

 unterschiede doch die mittleren Zellengrossen dieselben bleiben." 

 Strasburger (1893) emphasizes the fact that, although individuals of 

 the same species always show the same size of embryonic nuclei and 

 cells, regardless of variations in the size of their growing points, 

 varieties of these same species may differ greatly from each other. 



The conclusions of Sachs and Amelung, in regard to the " fixed size 

 of specific organ-cells," are supported by those of a number of other 

 investigators. For example, Conklin (1896) finds that, in dwarfs of 

 Crepidula plana, the cells are of approximately the same size as in 

 normal forms, and (1898) that sexually dimorphic individuals of this 

 species, although differing greatly in body size, are composed of cells 

 of similar sizes. Rabl (1899) considers that the cells of the crystalline 

 lens vary appreciably in number, but not in size. The work of 

 Driesch (1898 & 1900) is particularly suggestive. He shows that in 



1 This paper was presented in preliminary form at the Columbus meeting 

 of the American Association, December, 1915. 



