Vlll AUTHOR'S PREFACE. 



respiration under altered conditions of pressure, have 

 been almost entirely rewritten. I have to acknowledge 

 valuable assistance given to me by Mr. Leonard Hill, F.E.S., 

 and Dr. Pembrey, in the chapter on respiration, and by 

 Mr. A. W. Cadrnan, F.B.C.S., in the new account given of 

 the cranial nerves. 



W. D. HALLIBURTON. 



KING'S COLLEGE, LONDON, 

 April, 1901. 



