INTRODUCTION 9 
For the opportunities granted us for travel and investigation, we also desire 
to express our appreciation to the following gentlemen through whose courtesy 
and assistance our work was greatly facilitated. 
To Secretary of State Frank B. Kellogg and Assistant Secretary of State 
William R. Castle, Jr.; the American Ambassador to Great Britain, Alanson B. 
Houghton; and the American Ambassador to Belgium, William Phillips, — 
for diplomatic courtesies and arrangements with relation to the itinerary of the 
Expedition in Liberia, Belgian and British territory. 
To President Charles Dunbar Burgess King, Secretary of State Edwin 8. 
Barclay, and the other members of the Cabinet of Liberia, — for many cour- 
tesies and much governmental assistance, without which many of our investi- 
gations in Liberia would have been impracticable. 
To the Honorable Reed Paige Clark, Chargé d’ Affaires, American Legation, 
for many courtesies, and for much valuable information and assistance furnished 
throughout our stay in Monrovia; also to Mr. Clifford R. Wharton, Secretary 
of the American Legation at Monrovia, for many courtesies. 
To Mr. Donald A. Ross, General Manager of the Firestone Plantations 
Company; Mr. William D. Hines, special representative of Mr. Firestone; 
Dr. G. Bouet, French Consul to Liberia; Mr. Max Dinklage, German Consul to 
Liberia, Dr. Paul T. Willis of the Firestone Plantations Company; Bishop 
Campbell and Mr. Plenyono Wolo of Monrovia; and Messrs. Donovan and 
Webster of the American Church Mission at Cape Mount, — for courtesies and 
advice or assistance in Liberia. 
To Premier Ministre Jaspar of Belgium; M.-N. Arnold, Administrateur des 
Colonies; and M.-E. Leplae, — for diplomatic courtesies and exceptional oppor- 
tunities granted, and for arrangements made to facilitate our travel throughout 
the Belgian Congo. 
To Dr. J. Derscheid of the Congo Museum in Brussels, — for courtesies 
extended in connection with the Museum, and assistance given in the Belgian 
Congo in the region of the Kivu volcanoes; Drs. J. Rodhain and A. Broden, 
of the School of Tropical Medicine, Brussels, for much advice in connection with 
our work in the Belgian Congo. 
To His Excellency Governor-General M. Rutten of the Belgian Congo; 
Commissaire General Beernaert, Acting Vice-Governor at Leopoldville; Gover- 
nor Moeller of the Province Orientale at Stanleyville; Governor C. Duchesne 
at Coquilhatville; Director Corbisier of the Botanical Gardens at Eala; and 
Dr. R. Mouchet, Chief of the Medical Staff of the Belgian Congo at Boma, — 
for courtesies and special facilities and assistance in the Belgian Congo. 
To Professor F. Van den Branden, Director of the Laboratory at Leopold- 
ville; Dr. A. Duren, Chief of the Hygienic Service for the Province of Congo- 
Kasai, Kinshasa; Dr. LeDentu, Director of the French Pasteur Institute at 
Brazzaville; Dr. Strada at the Native Hospital at Coquilhatville; Dr. P. Stoner, 
Botanical Garden, Coquilhatville; Dr. Indorff at Alberta; Dr. Feys at Lisala; 
Dr. Clement C. Chesterman and Dr. K. Waller Todd at Yakusu; Dr. L. For- 
nara, Head of the Medical Staff and Doctors Donadio and Clevers at Stanley- 
