MATHEMATICAL CONTRIBUTIONS TO THE THEORY OF EVOLUTION. 
121 
be destroyed in a struggle for existence with those of the mother, and give rise to 
exclusive inheritance. And all these three processes may be going on within the 
same germ-plasm mixture at the same time ! Even without using the language of 
gemmules, processes analogous to the above must be supposed to take place. Thus a 
quantitative “ mixture of germ-plasms ” becomes a mere name, screening a whole 
range of mechanical processes; and very possibly a new one could be found for each 
new form of heredity as it occurs. Such processes like the old ones would still 
remain without demonstrable reality under the veil of “ mixture of germ-plasms.” 
What I venture to think we require at present is not a hypothetical plasmic 
mechanics, but careful classifications of inheritance for the several grades of rela¬ 
tionship, for a great variety of characters, and for many types of life. This will 
require not only the formation of records and extensive breeding experiments, but 
ultimately statistics and most laborious arithmetic. Till we know what class of 
characters blend, and what class of characters is mutually exclusive, we have not 
within our cognizance the veriest outlines of the phenomena which the inventors of 
plasmic mechanisms are in such haste to account for. Such inventors are like planetary 
theorists rushing to prescribe a law of attraction for planets, the very orbital forms of 
which they have not first ascertained and described. Without the observations of 
Tycho Brahe, followed by the arithmetic of Kepler, no Newton had been possible. 
The numerical laws for the intensity of inheritance must first be discovered from wide 
observation before plasmic mechanics can be anything but the purest hypothetical 
speculation. 
Appendix I. 
Tables of Colour Inheritance in Thoroughbred Racehorses, extracted by Mr. Leslie 
Bramley'-Moore from Weatherby’s Studbooks. 
Table of Colours. 
1 = black (bl.) 
2 = black or brown (bl./br.). 
3 = brown or black (br./bl.). 
4 = brown (br.). 
5 = brown or bay (br./b.). 
6 = bay or brown (b./br.). 
7 = bay (b.). 
8 = bay or chestnut (b./ch.). 
9 = chestnut or bay (ch./b.). 
10 = chestnut (ch.). 
11 = chestnut or roan (ch./ro.). 
12 = roan or chestnut (ro./ch.). 
13 = roan (ro.). 
14 = roan or grey (ro./gr.). 
15 = grey or roan (gr./ro.) 
16 = grey (gr.). 
R 
YOL. CXCV.—A. 
