DOES HYBRIDISATION INCREASE FLUCTUATING VARIABILITY ? 99 
important little paper by Mr. Hurst (3) concerning the heredity of 
coat-colour in horses. 
____ Darbishire’s (4) change of front with regard to the interpretation of the 
Mendelian laws shows the awakening of a better understanding as to 
the value of pure statistics for biology. 
It is beyond all doubt that statistical methods have very great 
importance in many points of research in heredity, but the conditio 
sine qua non is, as always, a previous competent sifting and arrangement 
of the data to be used. The questions which interest us in heredity 
must be formulated biologically, if an answer, biologically applicable, is 
to be given. But this point has been almost totally neglected by the 
biometricians. 
If anybody makes a study as to the speed of railway-cars, he will of 
course regard every train or every type of train separately : express trains, 
local trains, goods trains, and so on. He can then collect details and 
statistics needful for understanding the traffic as a whole, the train- 
types, &c. But what would be said of an inquirer who, for solving the 
problem, collected statistics as to the speed of the different carriage- 
classes, first, second, and third class, and by this method found out that 
the average speed of the first-class car was much greater than the 
for in the express trains (on the 
Continent at least) there are only, or almost always only, first and second 
class cars, while in the local trains the third-class car is in the majority. 
The result of these statistics would certainly be a truth also, but it 
would be without any real interest: indeed it would be quite misleading 
as to matters of railway traffic. I must confess that the main part of 
biometrical work in questions of heredity somewhat resembles such pre: 
posterous statistics. 
The mathematical terms in which biometricians have tried to express 
the “ancestral influence”’ may in reality be a true result of statistics ; 
but in these statistics the data have mostly not been analysed in a 
biologically reasonable manner. It is much to be regretted that biome- 
tricians, although fairly compelled by the force of argument to see the 
faults of their premises, still persevere in their “antibiological” pro- 
ceedings. They seem to confound the statistics serviceable for insurance 
purposes and also possessing great scientific interest for social questions 
with the exploration of fundamental laws of biology or physiology. 
In the science of biology the rediscovery of Mendel’s laws, and the 
highly important development of Mendelian researches in the last few 
years, have entirely displaced the general biometrical conception of 
ancestral influence: it is now evident that in Mendelian cases not the 
personal qualities of the ancestors but the nature of the zygotes is the 
essential factor in heredity—and the nature of the zygote is not a mere 
function of ancestral qualities. Statements of averages are here, of 
course, without value for the experimenting biologist. 
The inadequacy of the assumed “ ancestral influence” is now 
granted by all biologists who in their breeding experiments are operating 
with “traits” which are characterised qualitatively. All the famous 
Mendelian examples from peas, the results of Correns’, Miss Saunders’, 
Tschermak’s and De Vries’s experiments (with plants), hich 
ry 
