260 CONSUMPTION 



that the development of motor transport and equally also of farm 

 tractors 1 tends to cheapen and to increase the efficiency of the whole 

 business, not only of production, but also of the marketing and 

 distribution of foodstuffs. 2 



II. 



The world depends upon animal industries for its supplies not 

 only of animal foodstuffs, but also of such joint products as leather, 

 skins, wool, glue, and hair ; and the prices of animal foodstuffs, 

 and in some measure the extent and the nature of animal industries 

 depend upon the demand for these joint products. 3 If it is supposed 

 for a moment as before, that the white populations of the world 

 consumed little or no animal foodstuffs, the demand for wool and 

 leather might still remain, hut farm animals would be specialised 

 for the production of these articles without any regard to their 

 capacities for the production of meat and other foodstuffs. The 

 demand for animal foodstuffs being what it is, the production of 

 wool and leather tends to be incidental to that of the former in 

 animal-rearing industiies ; an exception arises, however, in some 

 cases of extreme specialisation in sheep-rearing, when wool becomes 

 the main product and tallow and meat the subsidiary joint products. 

 In the main, however, apart from specialised wool-sheep, these 

 joint products are inseparable from the production of animal food- 

 stuffs, though the quantities produced do not benr a constant ratio 

 to the quantities of animal foodstuffs produced. As will be seen 

 later, this ratio tends to decline as time passes. Now the present 

 consumption of these joint products tends to overtake the produc- 

 tion, and the demand for them, therefore, tends to stimulate the 

 business of rearing the animals that produce them. To return to 

 the supposition above made, if the demand for meat were to vanish, 

 the demand for these joint products remaining unaltered, then 

 the total number of wool and leather producing animals would 

 have to be maintained at nearly the present level, unless by breeding 

 animals exclusively for these products a higher return per animal 

 were obtained. Under this supposition meat would be a by- 



1 Motor power, whether derived from steam or from internal combustion 

 engines, can be, and actually is, widely used on farms not only for the traction 

 of cultivators and other moving implements, but also as a means of driving 

 stationary machines such as threshers, chaff-cutters, slicing and pulping 

 machines, pumps, and even milking machines and separators. 



2 This depends, of course, on the condition that motor power is cheaper 

 than horse power, and this in its turn depends upon a lower relative cost per 

 unit of work done, of mineral oil and its substitutes, than of oats and other 

 feedstuffs for horses. 



3 But compare the following quotation which bears on what follows : 

 " There are very few joint products the cost of production of which together 

 is exactly the same as that of one of them alone. So long as any product of 

 a business has a market value, it is almost sure to have devoted to it some 

 special care and expense which would be diminished or dispensed with, if 

 the demand for that product were to fall very much." Marshall, Principles, 

 Book V., VI., para. 5, . 



