The Various Forms of Variability. 51 



viduals should be called Convariants, successive ones De- 

 variants;^ and individuals departing widely from the 

 mean are often called variants. 



Individual variability is exhibited by size, weight and 

 number; Ludwig^s countings on flowers conform to Que- 

 telet's laws as accurately as the anthropological meas- 

 urements of that great writer himself. Variations in 

 size and weight should be called quantitative, and Bate- 

 son has proposed for variation in numbers the name 

 discontinuous or meristic.^ 



Darwin asserted over and over again that this form 

 of variability ^'perpetually occurs." It could therefore 

 be described as perpetual or incessant, and tliis idea 

 seems to me to be best expressed by the word continu- 

 ous."' 



Individual variability, when tested by sowing, reverts 

 to its original mean, the forms of its variants are con- 

 nected together, are coherent and not discontinuous. It 

 is centripetal inasmuch as the variations are grouped most 

 densely round a mean. Finally — and this is very im- 

 portant — it is linear; because the deviations occur in 

 only two directions — less or more. This fact has given 

 rise to the expressions plus-variations and minus-varia- 

 tions. 



It is to the selection of the material afforded by in- 

 dividual variability that the origin of many improved 



* Alfred Ploetz, Die Tilchtigkeit iinserer Rasse iind dcr Schuts 

 der Schzvachen, I, 1895, P- 3i- 



^Materials for the Study of Variation. 



^ I have used the terms continuous and discontinuous in this 

 sense in my essay Ueher halbe Galton-Curven als Zcichen discon- 

 tinuirlichcr Variation. (Berichte d. d. Bot. Gcs., 1894, Bd. XII, 

 Heft 7). Bateson uses the word in a sHghtly different sense inas- 

 rnuch as he employs the term continuous solely for quantitative, and 

 discontinuous for meristic variations {Materials for the Study of 

 Variation, 1894). 



