430 CHARLES RUSSELL BARDEEN 



Wiiitrebert, ('06) states that radium emanation within certain 

 Umits, the maximum of which is higher than that in any natural 

 radio-active waters, stimulates the development of amphibian 

 eggs and larvae. Eggs, however, require weaker solutions than 

 larvae and will die in solutions favorable to the latter. 



Having thus briefly' reviewed the physiological action of the 

 X rays on various tissues we may proceed to examine a little 

 more closely into the nature of the cytological disturbances pro- 

 duced by the rays. 



Various experiments on ennucleated unicellar organisms have 

 proved that non-nucleated protoplasm retains for some time the 

 power of sensory-motor response and of simple metabolic activity. 

 The power to digest substances, is however, impaired; the power 

 to secrete substances and the power to repair wounds are reduced ; 

 the power to form new chlorophyl granules is lost and the power 

 of cellular reproduction is destroyed.^ 



The effects of exposure to the X rays resemble so closely the 

 effects produced by removing nuclei from cells that one is 

 led at once to infer that the action of these rays is primarily 

 exerted on the cell nuclei. The alterations exhibited in the 

 cytoplasm may as a rule be referred to disturbances, visible or 

 invisible, produced in the nuclei. In the main, the nuclear and 

 cytoplasmic disturbances produced by exposure to the rays are 

 exhibited not in the cells exposed but in daughter or granddaugh- 

 ter cells or in cells of more remote generations. This leads us 

 to believe that, as a rule, it is not so much the dynamically active 

 substances in the nucleus as it is the reserve determinants which 

 are injured by the exposure. On the other hand, the sensitive- 

 ness of ovarian ova and of the spermatocytes of the first order 

 during the period of rapid growth seems to show that the powers 

 of constructive metabolism exerted by the nuclei are quite sus- 

 ceptible to disturbance by exposure to the X rays. It is highly 

 probable that the most complex of organic substances are the 

 substances which go\^rn differential morphogenesis and that of 



'For ;i review of the literature on this subject see Wilson — The Cell; Verworn 

 AUgenieine Physiologie. 



