142 Heredity and Eugenics 



DeVries' pangene complex are no better and perhaps no 

 worse than the hypothesis that racial memory is the basis 

 of inheritance, or that the complex or harmonious equi- 

 potential systems of Driesch "explain" the phenomena. 



As far as the facts of development and heredity are 

 concerned, they might go on indefinitely repeating any 

 given series of events, but there would be only one type of 

 organism, alike at any and all points in the genetic chain. 

 Adequate evidence that there have been changes in this 

 series of events in the past and that changes are now going 

 on is found in the array of specific organic forms that exist 

 and have existed through geological history. How have 

 these changes been produced ? 



The nineteenth-century biology formulated its hypothe- 

 ses around two widely different concepts; an extreme 

 transmission hypothesis in which modifications arising in 

 peripheral parts soma, i.e., personal peculiarities developed 

 in life are transmitted to the progeny, through being in 

 some manner incorporated into the germinal constitution of 

 the race ; and the hypothesis that changes in the race arise 

 primarily in the germinal substance itself and appear later 

 in the soma. 



The idea of the peripheral origin of variations through 

 the stress of the conditions of life dates back to Buff on, 

 Erasmus Darwin, and Lamarck, whose ignorance of things 

 now common knowledge had led them to express the opinion, 

 backed by much circumstantial evidence, that the condi- 

 tions of life, especially when changed, produced variations 

 which were heritable in the race. Darwin advanced the 

 hypothesis of an atomistic mechanism whereby this trans- 

 mission could conceivably be produced and upon this pro- 

 visional hypothesis of Pangenesis have been based all 



