764 TRANSACTIONS OF SECTION M. 
The importance of this work is not to be measured only by the readiness with 
which the seed of the new varieties has been tried by farmers and the extent to 
which it has succeeded. The demonstration of the inheritance of immunity to 
the disease known as yellow rust, the first really accurate contribution to the 
inheritance of resistance to any kind of disease, inspires hope that a new method 
has appeared for the prevention of diseases in general. i 
Biffen’s work too shows the enormous value of co-operation between the in- 
vestigator and the buyer in defining problems-connected with the improvement of 
agricultural produce. It is open to doubt if a committee of farmers would have 
been able to define the problems of English wheat production as was done by the 
Millers’ Committee, and in the solution of any problem its exact definition is half 
the battle. Mackenzie and Marshall in their work on the ‘ Pigmentation of 
Bacon Fat’ and on the spaying of sows for fattening, have found the great value 
of consultation with the staffs of several large bacon factories. There seems to 
be in this a general lesson that before taking up any problem one should get into 
touch not only with the producers but with the buyers, from whom much useful 
information can be obtained. 
I feel that Bifien’s work has borne fruit in still another direction, for which 
perhaps he is not alone responsible. Twenty years ago Agricultural Botany took 
a very subsidiary position in such agricultural examinations as then existed. In 
some of the agricultural teaching institutions there was no botanist, in others the 
botanist was only a junior assistant. It is largely due to the work of Biffen and 
the botanists at other agricultural centres that botany is now regarded as perhaps 
the most important science allied to agriculture. 
I must here repeat that I am not attempting to make a complete survey of all 
the results obtained in the last twenty years. My object is only to pick out 
some of the typical successes and failures and to endeavour to draw from their 
consideration useful lessons for the future. So far I have not referred to the 
work which has been done in the nutrition of animals, and I now propose to 
couclude with a short discussion of that subject. The work on that subject 
which has been carried out in Great Britain during the last twenty years has 
been almost entirely confined to practical feeding trials of various foods or 
mixtures of foods, trials which have been for the most part inconclusive. 
It has been shown recently that if a number of animals in store condition are 
put on a fattening diet, at the end of a feeding period of twelve to twenty weeks 
about half of them will show live-weight increases differing by about fourteen per 
cent. from the average live-weight increase of the whole lot. In other words, the 
probable error of the live-weight increase of a single fattening ox or sheep is 
fourteen per cent. of the live-weight increase. This being so, it is obvious that 
very large numbers of animals must be employed in any feeding experiment 
which is designed to compare the feeding value of two rations with reasonable 
accuracy. For instance, to measure a difference of ten per cent. it is necessary 
to reduce the probable error to three per cent. in order that the ten per cent. 
difference may have a certainty of thirty to one. To achieve this, twenty-five 
animals must be fed on each ration. Those conversant with the numerous - 
reports of feeding trials which have been published in the last twenty years will 
agree that in very few cases have such numbers been used. We must admit then 
that many of the feeding trials which have been carried out can lay no claim to 
accuracy. Nevertheless, they have served a very useful purpose. From time to 
time new articles of food come on the market, and are viewed with suspicion by 
the farmers. These have been included in feeding trials and found to be 
safe or otherwise, a piece of most useful information. Thus, for instance, 
Bombay cotton cake, when first put on the market, was thought to be dangerous 
on account of its woolly appearance. It was tried, however, by several of the 
agricultural colleges and found to be quite harmless to cattle. Its composition 
is practically the same as that of Egyptian cotton cake, and it now makes on 
the market practically the same price. 
Soya-bean cake is another instance of a new food which has been similarly 
tested, and found to be safe for cattle if used in rather small quantities 
and mixed with cotton cake. The price is now rapidly rising to that indicated 
by its analysis. Work of this kind is, and always will be, most useful. Trials 
with few animals, whilst they cannot measure accurately the feeding value 
