TWENTIETH ANNUAL REPORT 83 
the reptiles were prepared during the year, and the card index 
system was increased in value by the addition of data relating 
to longevity, growth and increase of weight. 
The Curator has continued his motion picture studies of 
reptiles at night, photographing many interesting traits by mer- 
cury-vapor light. Among the results were moving picture films 
of several species of tree toads when singing and enormously 
distending the throat, the complete and previously unknown life 
history of the marbled salamander, the emergence of five differ- 
ent species of snakes from the eggs, and greatly magnified scenes 
of the feeding habits of small reptiles and amphibians. Motion 
picture studies of insects and their near allies resulted in scenes 
of the stridulating species while “singing,” and magnified views 
of development and transformations. 
On October 26, 1915, Dr. Francis G. Benedict, Director of 
the Nutrition Laboratory of Carnegie Institution of Washington, 
began a series of very elaborate experiments at the Park, for the 
study of the metabolism of mammals and reptiles. Dr. Benedict’s 
laboratory apparatus was first set up in the tortoise room of the 
Reptile House, and his researches will continue far into the year 
1916. 
Dr. Benedict thus describes, in precise terms, the character 
of these experiments: 
“In connection with the researches on human nutrition 
carried out at the Nutrition Laboratory of the Carnegie Insti- 
tution of Washington the necessity for a study of the funda- 
mental laws governing heat production in the living organism 
became apparent. Of the numerous factors influencing vital 
activity, particularly as indicated by the oxidation of material 
in the body and the accompanying production of heat, factors 
such as body temperature and the relative proportion between 
the active mass of protoplasmic tissue and inert body fat are 
of greatest significance. 
“Subsidiary questions, such as the nature of the integument, 
the insulating character and density of fur and feathers are, as 
yet, practically unknown. While the greatest proportion of the 
researches in the Nutrition Laboratory are confined to observa- 
tions on human subjects, the rich supply of material in the whole 
range of zoology in the New York Zoological Park led to the 
inception of a research designed to study the gaseous metabolism 
of animals of widely varying species. An elaborate and deli- 
