SECTIONAL TRANSACTIONS.—M, M*. §21 
in butter or cheese ; and, in normal times, the farmers engaged in wheat production, 
cotton growing, and the plantation industries. 
In advocating the need for specialisation in the depressed mixed farming districts 
of England to-day, there is no suggestion that men should necessarily give up livestock 
farming, as did Prout and Baylis, to concentrate on corn and clover crops, nor that 
they should give up arable cultivation to concentrate on livestock products in one 
form or another, as so many have done during the last fifty years. Either course may 
be recommended to consideration in certain circumstances. In general, however. 
the implication of the specialisation theory is that farmers should decide what it is 
that their farms are best fitted to produce, having regard only to soil, climate, trans- 
port, market and other economic factors, and that they should then apply themselves 
to the production of these things in the cheapest possible way. It may be that the 
bare fallow should replace the fodder crops and that the sheep should be relegated to 
the grass land; that the farmyard manure should be sold to the market gardener, 
and that artificials should do its work; that bullock-feeding should be abandoned, 
and straw sold if a market can be found for it. Briefly, the farmer should disabuse 
his mind of the idea that the foundations of mixed farming as he has learnt them are 
fixed and immutable. On the contrary, he and his advisers should reconsider the 
economics of production in a new light—the light that agricultural science has shed 
upon his problems. 
DEPARTMENT OF HORTICULTURE (M*). 
Thursday, September 24. 
Discussion on Plant Breeding :— 
Sir Daniet Hatt, K.C.B., F.R.S.—Introductory. 
Mr. M. B. Crane.—Genetics in relation to Pomology. 
This paper gives an account of the investigations on cultivated fruits in progress 
at the John Innes Horticultural Institution. They are concerned with such problems 
as fertility and vigour and genetical analyses of various physiological and morpho- 
logical characters. ; 
Briefly, the investigations involve :— 
1. Incompatibility in cherries, plums and apples; its behaviour and inheritance. 
In the diploid cherries the results so far obtained are in accordance with the genetic 
interpretation of incompatibility based on a series of oppositional factors, as advanced 
by East and Mangelsdorf in Nicotiana, Lehmann in Veronica and Sirks in Verbascum. 
In the hexaploid plums further complications occur, and these appear to be directly 
due to the polysomic condition of the factors which determine incompatibility. From 
crosses between many of the diploid cherries it is now possible to predict how the 
resulting offspring will behave amongst themselves and with their parents with respect 
to incompatibility. 
2. Generational sterility in Prunus, Pyrus and Rubus. A higher degree of fertility 
is required to give a productive yield in plums, cherries and raspberries than in apples 
and pears. 
3. Morphological sterility, i.e. the abortion or suppression of sex organs. In the 
raspberry sex forms are the result of genetic differentiation. Many of our horticultural 
varieties, though themselves hermaphrodite, are heterozygous for sex, and in breeding 
experiments hermaphrodite, female, male and wholly sterile plants appear in 
mendelian proportions. 
4. The breeding of the above-named fruits, also Ribes and Fragaria, in order to 
determine the genetic constitution of varieties, and the mode of inheritance of various 
characters. 
In the diploid raspberry two factors are concerned with sex, two with colour and 
one with hairiness. FM is $, F 9, M & and mf neuter. The male condition is 
correlated with obtuse foliage and approximates to R. idaeus obtusfolius Willd. The 
segregation with respect to the male organs is not so sharply discontinuous as that of 
the female organs. 
The colour of the spines is correlated with the colour of the fruits. Red- and 
tinged-spined forms have red fruits, green-spined forms apricot or yellow fruits. 
