AN EXPERIMENTAL STUDY OF ACCLIMATION TO 

 TEMPERATURE IN PLANARIA DOROTOCEPHALA. 



ELLINOR HELENE BEHRE. 



TABLE OF CONTENTS. 



I. Introduction 277 



Summary of the Literature 277 



Purposes of the Paper 279 



II. Material, General Methods and Terminology 280 



III. General Observations 281 



IV. Susceptibility 282 



A. Long Time Acclimation 284 



B. Short Time Acclimation 287 



V. Carbon DioxiHe Production 293 



A. The Colorimetric Method 293 



B. The Biometer Method 298 



v I. Influence of Temperature on Head-Frequency. . 300 



A. Direct effect of altered temperature 300 



1. During the Entire Period of Regulation 300 



2. During the First Few Hours of Regulation 305 



B. An Analysis of Acclimation by the Method of Head-Frequency. . 308 

 VII. Discussion 309 



VIU. Summary 313 



I. INTRODUCTION. 



It is a familiar fact that within certain limits within which the 

 organism can continue to function normally, metabolic rate 

 varies directly with temperature. As far back as 1865, Sachs 

 (1865) studied the effect of rise in temperature upon a great 

 number of biological phenomena and with a great variety of 

 material, and came to that general conclusion. Very accurate 

 data upon the rate of growth were obtained by Fere (1894) 

 working with hen's eggs; upon rate of activity of protoplasm by 

 Nageli (1860), Schultze (1863), Hofmeister (1867), and others, 

 and especially by Velten (1876) who made an accurate quantita- 

 tive determination of the effect of temperature upon the activity 

 of chlorophyll grains in Elodea, Vallisneria and Chara; upon 

 oxygen absorption, by Treviranus (1831) working on the honey- 

 bee; upon carbon dioxide excretion, by Rossbach (1872) in studies 

 on the contraction rate of vacuoles in various protozoa; and 



277 



