Generally from 5 to 20 per cent. of the plants produced by seed as commonly grown either by the farmer himself or the seedsmen, though they may be alike in more conspicuous characteristics, will show varietal differences of such importance as to affect more or less materially the value of the plant for the conditions and the purposes for which it is grown. In a book like this it is useless to attempt to give long varietal descriptions even of the sorts commonly listed by seedsmen, since such descriptions would be more a statement of what the writer thought seed of that variety should be rather than of what one would be likely to receive under that name. CHAPTER XVII Production for Canning =Growing for canning= has many advantages over growing for market. Some of these are that it is not necessary to start the plants so early, that they can be grown at less cost, and set in the field when smaller and with less check, and on this latter account are apt to give a large yield. It is not necessary to gather the fruit so often, nor to handle it so carefully, while practically all of it is saleable. For these reasons the cost of production is lower and it is less variable than with crops grown for market. Still farmers and writers do not agree at all as to the actual cost. It is claimed by some that where the factory is within easy reach of the field the cost of growing, gathering and delivering a full yield of tomatoes need not exceed $12 to $18 an acre, while others declare they cannot be grown for less than $40. Nearly one-third of this cost is for picking and delivering, and varies more with the facilities for doing this easily and promptly and with the yield than with crops grown for market. A large proportion of the crops grown for canning are poorly cultivated and unwisely handled, so that the average yield throughout the entire country is very low, hardly exceeding 100 bushels an acre. But where weather and other conditions are favorable, and with judicious cultivation, a yield of 300 to 800 bushels an acre can be expected. I have known of many larger ones.