90 CHARLES PACKARD 



radium radiations. Although the matter was not chemically 

 determined, it seemed probable that the lecithin was broken up 

 into cholin and tri-methyl-amine and other end products of leci- 

 thin decomposition. Lecithin has been found by many investi- 

 gators in all cells, especially in egg yolk, spermatozoa, pollen 

 cells, plant spores, growing buds, and in all rapidly growing tissue. 

 If then, it is destroyed such cells must necessarily be unfavorably 

 affected. 



Against this hypothesis can be raised a number of objections. 

 In the spermatozoon there can be very little lecithin, and any 

 amount that is destroyed would be so small as to be nearly negli- 

 gible. Yet Hertwig has stated that exposure of frog sperm for 

 one minute is sufficient to produce some abnormality in the em- 

 bryo. It is hard to imagine that this is due to the amount of leci- 

 thin decomposed in so brief a period. On the other hand, the egg 

 contains a relatively enormous quantity, so that the effect should 

 be correspondingly greater, yet such is not the case in the frog. 

 The experiments of Bardeen show only a slightly greater injury 

 when the egg is exposed. It is also found that the fertilized egg, 

 when radiated, develops very abnormally even though the expo- 

 sure is brief. These facts indicate that the lecithin hypothesis 

 cannot explain all of the phenomena although the decomposition 

 of the lecithin under radiation is an actual fact. 



The second hypothesis, advanced by O. Hertwig is called by 

 its propounder a 'Biological hypothesis' although fundamentally 

 chemical in its nature. It is assumed that the radium radiations 

 affect only the chromatin and that all the abnormalities that 

 result from radiations arise in consequence to the injury to that 

 substance. The chromatin, under the influence of the radiations 

 produces a 'contagium vivo' which acts like a living ferment in 

 that it increases at each cell division. Thus an originally small 

 amount generated in the sperm will make itself felt after many 

 cleavages, while a large amount generated in the fertilized egg 

 will produce abnormalities almost at once. In cases in which the 

 spermatozoa have been radiated for a long time it is assumed that 

 the 'contagium vivo' has increased to such an extent that it has 

 killed itself and at the same time affected the dividing power of 



