190 PHYSIOLOGICAL CLASSIFICATION OF TISSUES. 



section. From this experiment Schwendener places the strength 

 of the bast of Phormium tenax at 20 kilograms per square milli- 

 meter. 1 



527. The tables in the notes show that good bast equals good 

 iron in its tensile strength within the limits of elasticity, while in 

 its breaking-weight it is greatly exceeded by the latter. Schwen- 

 dener well remarks that Nature has given her whole care to pro- 

 viding that these mechanical elements should be strong within 

 the limits of elasticity, and with good reason ; for beyond those 

 limits the plant gains nothing by greater strength. Attention is 

 called also to the great difference between bast and the metals 

 with regard to their elongation under weight. 



1 The results of experiments made with the bast of various plants in the 

 manner described are given below. Most of the cases cited are from Schwen- 

 dener ; others are from Haberlandt (Physiologische Pflanzenanatomie, p. 105). 

 The. determinations for metals are from Weisbach. 



These should be compared with the results of determinations made with 

 other materials : 



