CONTENTS 



I 



t PAGE 



ON A PIECE OF CHALK [1868] 1 



(A Lecture delivered to the working men of 

 Norwich during the meeting of the British 

 Association.) 



II 



THE PROBLEMS OF THE BEEP SEA [1873] 37 



III 



ON SOME OF THE RESULTS OF THE EXPEDITION OF H.M.S. 

 "CHALLENGER" [1875] 



IV 



YEAST [1871] . 110 



