DOES HYBRIDISATION INCREASE FLUCTUATING VARIABILITY? 111 
an intelligent reader, that one of the tendencies of my present paper is to 
emphasise the fact that the biometrician’s methods of measuring the “ inteneity 
of heredity” are fallacious not only when applied in “ predicable cases’ 
(Darbishire p. 37), but also—from a biological point of view—when applied in 
* non-predicable cases.’’ These comprise all the non-analysed cases (including 
what may be non-analysable), concerning especially the quantitatively charac- 
terised highly fluctuating traits. Here biometry has given us stones for bread, 
e.g. as to the understanding of the action of selection, as to the problem of 
discontinuous or continuous evolution, and soon. Iam quite in accordance with 
Mr. Darbishire when he says that “the true function of the biometrician is to give 
us statistics of average conduct where we cannot predict individual conduct.” And 
this may perhaps suffice for many important problems of sociology (with pleasure 
I will say “ biological sociology” if desired), but it has no value at all for the 
biology of heredity and ev sanen the aim of which is to elucidate the origin 
and conduct of the veritable types of organisms, the “ biotypes.’’ Here 
biology must try to make the “ non-predicable ’’ predicable, by a sound analysis 
avoiding statistics of heterogeneous impure masses. The biometrical “ truths ”’ 
as to such masses may be able to confuse the views of biologists just so much 
as Weismann’s speculations on the ‘“ All-sufficiency of Natural Selection ’’— 
both operating with false premises: impure masses regarded as homogeneous 
aggregations. 
Some REFERENCES TO LITERATURE. 
1. JoHANNSEN.—Arvelighedslerens Elementer. (Kobenhavn, 1905.) (Trans: 
lation in preparation.) 
2. Bateson.—Variation ‘and Differentiation. (Printed for the Author, 
Cambridge University Press, 1903.)' 
3. Hurst.—On the Inheritance of Coat Colour in Horses. (Proceedings of 
the Royal Society, B, vol. 77, p. 388, 1906.) 
4, DaArBISHIRE.—On the Supposed Antagonism of Mendelian to Biometrical 
Theories of Heredity. (Memoirs and Proceedings of the Manchester Lit. & Phil. 
Soc., vol. 49; Part II., Nr. 6, 1905.) 
5. De Vries.—Die Svalofer Methode zur Veredelung, &c. (Archiv fiir 
Rassen- und Gesellschafts-Biologie, 3 Jahrg., p. 325, 1906.) 
6. JOHANNSEN.—Ueber Erblichkeit in Populationen und in reinen Linien. 
(Jena, Fischer, 1903.) 
7. CHARLIER.—Researches into the Theory of Probability. (Lunds Univer- 
sitets Arsskrift, N.F. Afd. 2, Rd. 1, Nr. 5, 1906.) 
8. THIELE.—Theory of Observations (London, 1903); and Forelesninger 
over Almindelig Iagttagelseslere. (Kobenhayn, 1889.) 
9. DaveNporT.—Statistical Methods, with Special Reference to Biological 
Variation. (2nd Edit., New York, 1904.) 
10. PEarson.—On the Laws of Inheritance in Man. II. (Biometrika 
vol. 3, p. 131, ff. 1904.) 
11. De Vries.—Alimentation et Sélection. (Vol. jubil. Soc. biol. de Paris, 
1899.) 
12. Gatton.—Natural Inheritance. (London, 1889.) 
13. Pearson.—The Grammar of Science. (2nd Edit., 1900.) 
14. Lorsy.—Vorlesungen iiber Descendenztheorien. I. (Jena, Fischer, 1906.) 
15. E. Cur. Hansen.—Om Variationen hos Saccharomyceterne. (Med: 
delelser fra Carlsberg Laboratoriet V., 1900, p. 1.) 
16. Barzson.—Materials for the Study of Variation. (London, 1894.) 
17. It is here sufficient to refer to Bateson, Presidential Address to Section D, 
British Association’s Report, Cambridge, 1904, p. 574. 
18. Prate.—Review of my “ Erblichkeit in Populationen,” &e. in Archiv fiir 
