150 Prof. J. A. MacWilliam. On the [Oct. 24, 



A repetition of the process of raising the pressure sometimes causes 

 the maximum elongation to occur much earlier than before, e.g., with 

 the rise from 50 to 100 mm., or from 100 to 150 mm. At other times 

 there is simply a general increase in extensibility without the maximum 

 elongation coming early (0 — 300 mm.). (See Fig. 32.) 



Fig. 32.- — Elongation of contracted artery with rise of internal pressure, 

 0—300 mm. Length 16 mm. 



Relaxed Artery. — A relaxed artery tested in the same way shows a 

 vastly increased elongation when the internal pressure is raised. The 

 maximum elongation occurs with the first or second rise ; sometimes 

 the second and third are equal in extent. (Fig. 33.) 



Fig. 33. — Kelaxed artery which has been kept in blood for some days— tiil 

 contraction had passed off. Length 21 mm. 



A repetition of the rise of pressure shows an increased extensibility 

 -especially for low pressures. 



