THE RELATIONS OF BURSARIA TO FOOD 



II. DIGESTION AND RESORPTION IN THE FOOD VACUOLE, AND 

 FURTHER ANALYSIS OF THE PROCESS OF EXTRUSION 



E. J. LUND 



Zoological Laboratory of the Johns Hopkins University 



EIGHT FIGURES AND TWO PLATES 



CONTENTS 



Introduction 1 



Material and methods 3 



To what extent can yolk be considered a food for Bursaria? 5 



Protein digestion 8 



1. The food vacuole; formation and physical changes 8 



2. Chemical changes in the food vacuole 12 



3. Effect of quantity of vitellin eaten, upon the average velocity of 



digestion 15 



4. Effect of Congo red upon the average velocity of digestion, extrusion, 



etc 22 



Digestion and resorption of fat 26 



1. A demonstration of fat digestion and resorption in the food vocuole 



of Bursaria 26 



2. Role of fat in growth and energy requirement 28 



3. Is fat formed from vitellin or starch in Bursaria? 29 



The nature of some of the factors which bring about extrusion 30 



1. Experiments with paraffin oil and olive oil 30 



2. Effect of mass or volume upon the extrusion reaction 34 



Summary 38 



Literature cited 39 



INTRODUCTION 



To obtain exact information on the processes of metabolism in 

 single-celled organisms, an(^ particularly the Protozoa, experi- 

 mental procedure must be based upon simple, well defined and 

 reproducible conditions, so that the work may be repeated and 

 verified. Attempts to fulfill this requirement are subject to the 



1 



THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 17, NO. 1 

 JULY, 1914 



