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- 



