EFFECT OF CHEMICALS ON GROWTH IN 

 PARAMECIUM 



A. H. ESTABROOK 



From the Lahoratary of Experimental Zoology Johns Hopkins University 



With One Figure 



CONTENTS 



Introduction 490 



Material and Methods 491 



Growth in distilled water 492 



Effect of pure distilled water 492 



Effect of adding NaCl to the distilled water 494 



Growth in sodium chloride 497 



Preliminary experiments on the effect of NaCl on the form and dimensions of 



adults 498 



Direct measurement of growth after fission 501 



Role of osmotic pressure in effects of sodium choloride 504 



Comparative resistance of adult and young Paramecia to NaCl 508 



Are Paramecia in stages preparatory to division like adulter like the young in their 



resistance to the salt: 508 



Acchmatization to NaCI 509 



Effects of nicotine on growth 511 



Effect of nicotine upon adult Paramecia 511 



Effect of nicotine on growing Paramecia 513 



Different resistance of young and adults to certain concentrations 516 



Effects of strychnine on growth 516 



Effects of strychnine upon adult Paramecia 517 



Growth of Paramecium in strychnine after fission 518 



Comparative resistance of adult and young Paramecia to strychnine 521 



Effects of alcohol on growth 523 



Effect of alcohol on growing Paramecia 52 3 



Resistance of adult and young in alcohol 528 



Effect of food on growing Paramecia 529 



Summary and discussion 531 



Bibliography 534 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 8, NO. 4. 



