This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Many, if not most, growers like to save their own seed, especially when they happen to have a variety that seems to suit them particularly well. Whether it is better to save seed from early fruits or from those at the tail end of the crop may or may not be a matter of importance, but it may conceivably affect the future crops. Following natural laws, it would appear to be better to select for seed the finest fruits that first ripen in the summer, not only because they are the first, and consequently earliest, but also because they have been produced with the first rush of youth and vigour and their seeds are more likely to have a fine, free, and disease-resisting constitution. The older a plant gets, the more feeble it becomes, the slower it ripens its fruits, and it falls an easier prey to disease. Seeds saved from such a plant may inherit some of the weaknesses of its parent, and consequently yield poorer returns to the grower. Hence it may be assumed that if seeds are to be saved it would be better in every way to obtain them from the first well-ripened fruits of the season.
It is by no means easy to clean Tomato seeds, as they are firmly embedded in the mucilaginous pulp that is so difficult to detach. One of the best means of obtaining clean Tomato seeds is to cut away the outer rind and as much of the seedless pulp as possible. The remain-ing portion, full of seeds (there are from 100 to 300 seeds in each fruit), should be rubbed between the hands and afterwards placed in a vessel containing cold water. Hot or even lukewarm water should not be used, or the seeds may be caused to sprout. The liquid should be churned round and round with the hand or a stick. This will detach a certain amount of pulp, which can be skimmed off. The liquid may then be left for a few hours, at the end of which more pulp will be detached by churning, and can be removed. By repeating this operation on large quantities of seed and pulp, the latter is eventually separated from the former. The seeds should then be laid out on sheets of glass or tin or stiffish paper and allowed to dry. They should, however, be moved about with a knife blade occasionally to prevent them sticking to the surface. When thoroughly dry they may be rubbed between the hands with some silver sand and thus freed from all traces of dry mucilage.
Fig. 498. - Tomatoes in Handle Basket.
Another method is to cut the fruits in half and then prick out the seeds with the point of a penknife on to a piece of glass, afterwards washing and drying as before. The pulp may be converted into jam.