Note. — The articles collected in this volume were published 

 separately, as follows: Article I, October, 188-4; Article II, 

 March, 1885 ; Article III, August, 1885; Article IV, June, 1886; 

 Article Y, October, 1886; Article VI, July, 1887; Article VII, 

 April, 1888; Article VIII, July, 1888. 



