greater must be the non-productive consumption of food on main- tenance only.
Again in the later stages of fattening the law of diminishing re- turns operates in another fashion, in that the increase of weight may be put on as offa! fat of comparatively low value instead of as edible fat in the " meat " portions of the carcass. Much more exact information is therefore being sought as to the relations of the live weight increase to the progress in consumption of food and again to the changes in the composition of the carcass as the fattening process advances.
On the other side of the nutrition question recent work upon " vita- mines " and accessory food factors is found to have its application to questions of animal nutrition. Not only the health and growth of certain animals, notably pigs, is in practice affected by the deficiency of the foods habitually used in these accessory factors, but again the fats arising from the animals, e.g. lard, bacon, even milk and butter fat, may in their turn become deficient as human foods because of the lack of the accessory substances in the food of the animal. Enough work has been done to show that in certain special cases of indoor feeding of animals not only the broad energy- and tissue-forming properties of the food have to be considered, but also the supply of certain accessories energizers or detonators, whatever may prove to be their function. In practice the path of safety for all farm animals lies in a reasonably mixed diet, which includes some proportion of uncooked green food. Pigs and poultry have not in- frequently been sufferers from diets insufficiently supplied with vitamines.
Animal Breeding. Although in 1921 such progress had not yet been made with the very complex subject of animal breeding as to enable economic results to be obtained similar to those which had accrued in plant breeding, still the ground was being prepared by certain initial investigations for the mode of in- heritance of some of the desiderated qualities in domestic animals, e.g. size, prolificacy, quality of wool, etc.
Punnett, for example, in England has thrown some light on the inheritance of size in fowls and rabbits, and again on the inheritance of fur, but by far the most important work in this direction has been done by Pearl in Pennsylvania. In studying the inheritance of milk yields he has first of all endeavoured to obtain a single figure char- acterizing the performance of a cow, a sort of index number. By a study of commercial milk records he has constructed a type curve showing the variation in milk yield for a cow during successive cal- vings, whereby if its milk yield in any one year is known this figure can be corrected to give the milk yield in the standard year used for comparison. A similar type curve can be constructed for the period of a lactation, whereby the yield for the whole period can be de- duced from the yield ascertained during a particular month or less. Having thus obtained characteristic figures for cows, Pearl was in a position to compare the performances of cows with their offspring by different bulls. By tabulating all such comparisons obtainable with regard to a particular bull a characteristic mark is obtained for the bull. Some bulls are found always to bring about an increase in the milk production of the daughter over the dam ; other bulls which had a great repute in their day and a fine record in the show yard equally invariably gave progeny yielding less milk than their dams. The value of this work in connexion with milk recording and breeding is evident; indeed in Denmark for some years the underlying prin- ciple has been appreciated in that prizes are offered for bulls, the award being based upon the milk tests of the bull's progeny. The difficulty attaching to the application of these results lies in the disinclination of farmers to retain bulls for service for more than two or three years ; they are cast before there is any opportunity of test- ing the milk-producing quality of their offspring. (A. D. H.)
II. ADMINISTRATION AND LEGISLATION IN THE UNITED KINGDOM
As was inevitable, the World War gave rise in all countries to a great body of emergency enactments and temporary legisla- tion affecting agriculture. Beyond these, however, the years 1917-21 saw a large volume of legislation which aimed at the reorganization of agriculture in Great Britain, and also inaugu- rated a definite agricultural policy, the main features of which found expression in the Corn Production Act of 1917 and the Agriculture Act of 1920. The principles underlying these Acts first were set out in the report of the commission appointed in 1915 under Lord Milner, and still more fully in the report of the sub-committee of the Reconstruction Committee under the chairmanship of Lord Selborne.
Briefly, these committees found that the position of the United Kingdom had, as demonstrated by the war, fallen into great insecurity in consequence of the neglect of agriculture which had been going on during the previous 40 years. In 1872 the arable
land in the United Kingdom amounted to nearly 24,000,000 ac., and this had become by 1914 little more than 19,000,000 acres. The loss had been experienced chiefly in England and Wales, where the shrinkage had been nearly 4,000,000 ac., from 14,943,- oooto 10,998,000 acres. This represents a great decline in the gross production of food, because it has been abundantly demonstrated that an acre of medium land under grass does produce only about one-third of the meat or milk that can be obtained from the same land if it is put under the plough and the crops are con- sumed by stock. Moreover, whenever there is a definite shortage of food the production of meat is in itself a wasteful process, from seven to ten pounds of real food being consumed by the animal in making one pound of food in the shape of meat or milk. The only gain in meat production is that the animal is able to convert coarse fodder like straw and waste materials like millers' offals into human food, but an animal like a pig, which is largely fed upon barley and maize meal, equally edible by human beings, becomes definitely wasteful of the resources of the country when a real food scarcity is declared. The comparison between the productiveness of grass and arable land may perhaps be illus- trated most markedly by a consideration of the potato crop. Art average yield of potatoes in England is about 6j tons per ac., which represents over 2,000 Ib. of dry food when all allowances have been made for waste. Under grass the same land would not produce more than 120-150 Ib. of meat, i.e. about 100 Ib. of dry- food, or 160 gal. of milk, i.e. 170 Ib. of dry food. Nor does the animal food, pound for pound of dry matter, possess more than a slight superiority over the potatoes in its power of main- taining human beings.
Before the War. Roughly speaking, in the years immediately preceding the World War the United Kingdom was only pro- ducing about 42% of the food consumed by its people. The greater portion had to be imported, and this applied particularly to wheat of which only about one-fifth of the normal consump- tion was produced at home. This dependence of the nation upon external supplies of food was its great weakness revealed by the war. Not only was there the danger that the German submarine campaign might prove successful and force submission by starvation, but, even as it was, the country's effort was ham- pered by the necessity of allocating to food supply so large a proportion of the available tonnage needed for other purposes and of employing part of the naval strength to protect it. Again, the purchasing power and credit of the country were continually impaired by the enormous sums spent abroad for food.
The external food bill amounted to over 220,000,000 a year before the war, and during its latter stages this had risen to three times that sum. The enemy was not slow to realize that this was Britain's vulnerable spot. The attack failed, but the economic consequences pressed grievously upon Great Britain after the war. The recovery of Britain was deferred by the enormous purchases it must continue to make abroad in order to keep its people fed, and the sacrifices it must make in order to maintain the foreign exchange at a high level in order to meet these pur- chases.
It had often been argued that in case of emergency the grass lands of Britain constituted a great reserve of fertility which could be drawn upon for the growth of corn and other crops, but when the occasion came it was proved how little of this reserve was immediately available. Neither the men nor the horses, not even the buildings or the implements, required for arable farming, existed any longer. All the inertia of the farming community came into play against conversion, and despite the efforts of the State, armed with compulsory powers, proffering compensation against loss and assisting with fertilizers, seeds and machines, less than a further 2,000,000 ac. of grass lane 1 got broken up during the fateful years of 1917 and 1918. Once the art and means of arable farming have been lost, it is only slowly and at great expense that they can be improvised.
Concurrently with the decline in the production from British land in consequence of the conversion from arable into grass there had been a, corresponding decrease in the agricultural pop- ulation, which in England and Wales alone had fallen from
