FROM LAMARCK TO ST. HILAIRE 261 



recently been termed 'saltatory evolution' and 

 strongly opposed Lamarck's fundamental prin- 

 ciple that all transformation is extremely slow. 

 It is evident that this idea was suggested to him 

 by the sudden transformations observed in his 

 studies of congenital abnormalities. This enabled 

 him to maintain the principle of Evolution with- 

 out demonstrating the existence of intermediate 

 stages. The absence of connecting links and in- 

 termediate forms had begun to be a stumbling- 

 block to evolutionists; where, it was asked, was 

 evidence of a transition between amphibians and 

 reptiles, and between reptiles and birds? This 

 also enabled Geoffroy to avoid a difficulty he 

 himself raised, that characters of new forms of 

 life would not be maintained pure, owing to the 

 blends of interbreeding; these sudden saltations 

 or leaps from type to type secured the necessary 

 physiological isolation. Geoffroy thus anticipated 

 the now famous 'mutation theory' of Hugo de 

 Vries. 



As a rapid transformationist, Geoffroy was 

 not, however, an imitator of de Maillet, who, we 

 remember, believed in the transformation of adult 

 forms. St. Hilaire denied the possibility of these 

 rapid leaps in the adult condition, and believed 

 that they took place mainly in the embryonic or 

 germinal condition, where the underlying causes 

 of sudden transformation were profound changes 



