VI TRANSLATOR'S NOTE. 



I am especially indebted to Dr. Zimmermann for prepar- 

 ing, for this edition, notes on several important results of 

 very recent studies ; and I have added a few annotations of 

 the same sort, thus bringing the present edition as com- 

 pletely as possible up to date. All additions by the trans- 

 lator are enclosed in square brackets. 



WEYMOUTH HEIGHTS, MASS , July, 1893. 



