THE EFFECT OF RADIUM RADIATIONS ON THE 

 FERTILIZATION OF NEREIS • 



CHARLES PACKARD 



k THREE PLATES 



CONTENTS 



Introduction 85 



The nature of the radium radiations 86 



Historical review 86 



Methods 91 



The normal development of Nereis 92 



Experimental 9S 



a. The fertilization of normal eggs by radiated spermatozoa , . 93 



b. The development of eggs radiated before fertilization 98 



c. The development of eggs radiated after fertilization 100 



d. The development of eggs radiated before and after fertilization 106 



e. The development of eggs normally fertilized, and exposed to radium. . 107 



f . Subsequent development of the embryo 109 



g. Development of eggs radiated before and after fertilization with 



normal sperm 109 



Discussion 112 



Summary and conclusion 119 



Literature cited 121 



INTRODUCTION 



The radiations of radium have been used as a stimulus to proto- 

 plasmic activities from the time they were first discovered. The 

 early experiments were made with little knowledge of the nature 

 of the stimulus and with none whatever as to its probable effect on 

 living matter. It was found that the rays affected the tissues in 

 very different ways, acting as a stimulus to growth in some tissues, 

 and as an inhibitor in others. Thus, seedlings have, in some in- 

 stances, been accelerated in growth, and the action of certain 

 enzymes (pepsin, diastase, etc.) favored by exposure to the rays. 

 On the other hand, an exposure to radium produces a marked 

 retardation in the growth of certain tissues and a characteristic 

 degeneration in some of the cell constituents. The latter effects 



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THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 16, NO. 1 



