472 On the Latent Capacity for Mutation. 



disease, analogous to those cases in which parasites have 

 been observed as the causes of virescence.^ 



Monstrosities often differ from ordinary individual 

 variations in the fact that they are deviations on one side 

 only of the type of the species, whilst the latter deviate 

 from both sides of the mean. In this way we get, when 

 we have a sufficient number of instances of the same 

 monstrosity in a given species, the socalled half-Galton 



Fig. 107. Oenothera Lamarckiana. Fruit in the axil of a 

 deeply split double leaf; the flower from which this fruit 

 arose had the double number of sepals and petals and 

 stamens as a normal flower, and was elongate in trans- 

 verse section. 



curves.^ Polymerous flowers, 5-9 partite fruits, split 

 stigmas and even fasciation, all illustrate the same law.^ 

 But the majority of monstrosities are much too rare to 



"^ Een epidemie van vergroeningen, Kruidkundig Jaarboek, Gent, 

 T. VIII, 1896, p. 66. 



^ Berichte d. deutsch. Bot. Gesellsch., Bd. XII, 1894, p. 197-207, 

 with Plate X. 



^ See Sur les courhes Galtoniennes des monstruosiies, Bull. Scien- 

 tif. de la France et de la Belgique public par A. Giard^ T. XXVII, 

 p. 396, Avril 1896. 



