722 



NOTES 



93. Strength and elasticity of mechanical cells. Schwendener : I.e. [91 ]. pp. 

 9-16. Weinzierl : Sitzb. Wien, 76, 1877. F. Haberlandt : Wollny's Porsch 1., 

 No. 5. Firtsch : Her. 1, 1883. Sonntag : Landw. Jahrb. 21, 1892. Schwendener 



Ber. 12, 1894. p. 239. 

 99, 1909. 



Wiesner : Rohstofte (2nd ed.), Ch. XVIII. Sonntag : Flora, 



[94. The translation, in the text, of Tragmodul as " modulus of elasticity," 

 requires correction. In a foot-note to p. 151 of the original, Prof. Haberlandt defines 

 the Tragmodul as " the maximum load per unit cross-section, that can be supported 

 without the elastic limit being exceeded." The correct equivalent in English, there- 

 fore, is " load at the elastic limit," or (as it is more usually termed), simply, " elastic 

 limit." 



In the same foot-note Festigkeitsmodid is defined as " the [minimum] load per 

 unit cross-section which causes rupture." The best equivalent for this term is 

 " ultimate strength." 



Hence, on pp. 163 and 164 of the text, the terms " modulus of elasticity " and 

 " breaking strength " should everywhere be replaced by " elastic limit " and " ulti- 

 mate strength " respectively. In the quotation from Schwendener. on p. 163, 

 11 elastic limit " should also be substituted for " tensile strength." 



95. The mechanical principles underlying the arrangement of the stereome 

 were first explained by Schwendener in his classical treatise entitled Das mechanische 

 Prinzip. The objections raised by Detlefsen (Arb. Wurzb. 3) were refuted by Schwen- 

 dener in a paper Zur Lehre v. d. Festigkeit d. Gewachse (Sitzb. Berlin, 46, 1884). 

 Schwendener dealt principally with the vegetative organs of Phanerogams. Interest- 

 ing observations on the skeletal system of floral organs particularly of sepals and 

 petals have been made by Herzog (Uber. d. Systeme d. Festigung u. Ernahrung i. d. 

 Bliite (Inaug. -Dissert.), Freiburg [Switzerland], 1902). 



96. I have had considerable difficulty in finding suitable English equivalents for 

 the terms employed by German botanists in describing the various forms of mechanical 

 resistance. Terms such as " rigidity," " stiffness," etc., which are already to some 

 extent in use, are not sufficiently definite. My attempts to derive appropriate and 

 at the same time euphonious substitutes from Greek or Latin roots met with no 

 success. I therefore decided to make shift with words such as " inflexible," " in- 

 extensibility," etc., defining them in a particular sense for the purposes of the 

 physiological anatomist. When applied to a stem, therefore, " inflexible " must 

 be understood to mean, not " incapable of being bent," but '' offering resistance 



