118 CHARLES PACKARD 



attributed by Falta and Schwarz ('11) to enzyme activation. 

 Gager ('08) and Congdon ('12) have also found some evidence of 

 acceleration in growth, if the intensity of the radiation is not too 

 great. When Drosophila eggs are placed close to a strong prep- 

 aration of radium, their development is retarded. From these 

 experiments it may be concluded that many kinds of enzymes 

 may be activated but that the lytic enzymes are more stimulated 

 than those that play a synthesizing role. 



The decomposition of the nitrogenous compounds of the cell 

 is in part normal and in part abnormal. Lecithin breaks down 

 into cholin and finally into trimethyl amine, a reaction which 

 does not take place in life. But the decomposition of the nucleo- 

 proteids occurs constantly under normal conditions. Under the 

 influence of enzymes these substances are oxidized to nucleinic 

 acid and finally into some of the purin bases (guanin, hypoxanthin, 

 etc.). The reverse reaction also occurs, by which the complex 

 nucleo-proteid is built up again from the simpler materials. The 

 seat of this process is at the nuclear wall, where the nucleo-pro- 

 teids and the protoplasmic proteins adjoin. If, then, we assume 

 that under the stimulus of the radiation the katabolic changes in 

 the nucleo-proteids takes place at a more rapid rate than the 

 synthesizing reactions (an assumption that is warranted on the 

 basis of Wohlgemuth's results), we have an explanation of the 

 behavior of the radiated chromatin in breaking up into granules, 

 and failing to divide normally. The acceleration in growth, 

 found by Gager and Congdon when the material was exposed to 

 slight radiation, may be explained on the ground that under such 

 conditions the synthetic processes are stimulated, while under a 

 more intense radiation the opposite reaction obtains. 



The behavior of the radiated cells must, I believe, be inter- 

 preted in the light of the increased activity of these autolytic en- 

 zymes which act both on the chromatin and on the protoplasm. 

 A radiated spermatozoon is affected chiefly in its nuclear constitu- 

 ents which are broken down into simpler compounds. That these 

 are still acid is indicated by their staining reactions. When such 

 a cell enters the egg, the nucleus is unable to develop normally, 

 and to divide with the egg nucleus, because it cannot build up 



