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Show - 7 By ROBER i H. MOULTON at HE scientists are upsetting I many of our popular notions nowadays. The latest theory GST" they have disproved has to gKgt" do with the effect of cold up-on up-on plant life in our northern states. While we have always al-ways believed that Jack Frost was the arch enemy of plant life, and that If it were not for him we would have flowers flow-ers and fruits and grass perhaps all the year round, the scientists now tell us that Jack is In the main a beneficent benefi-cent old fellow. They admit that If lie comes too early or stays too late, his visit is likely like-ly to prove embarrassing. Yet if he did not come at all, which means If we did not have any cold weather, the majority ma-jority of plants inour northern latitudes lati-tudes would show slow growth in the spring. It is hard to believe that the effect of cold Is to stimulate rather than retard plant growth, but that Is what we are now Informed actually happens. Experts of the Department of Agriculture are responsible for this revolutionay theory. They back up the theory v. Ith the results of numerous numer-ous experiments, however, and results are what count. One fact stands clear In these experiments ex-periments the dormant condition of certain plants In winter is not the result re-sult of cold and freezing; moreover, cold stimulates the revival of life In the plant when spring comes. Such an explanation of the effect of cold Is new to the everyday reader, who is used to looking upon winter air as detrimental det-rimental to plant life, forcing the shrub Into a dormant state scarcely better than death. But healthy, husky blueberries which were In a government govern-ment greenhouse "went to sleep" just the same, despite the fact that the alt was kept at a growing temperature. The shrubs, It Is true, did not go tc bed so early as they did when Jack Frost used to hurry them off, and lr the warm greenhouse the plants went Into a dormant condition exactly Uk( that of others outside in the cold and snow. Moreover, they were lute In waking when spring came. Some, Indeed, In-deed, slept through the whole year. The Inference is that the plant's period pe-riod of dormancy Is a seasonal matter nut induced by the cold, but that the early and luxuriant growth cannot occur oc-cur unless the plant has been through a period o." chill temperature. Two interesting experiments were conducted with blueberry plants as proof of this. In the middle of February Feb-ruary n blueberry plant which had shed Its leaves and become dormant In a warm greenhouse maintained at a temperature of 70 degrees was repotted repot-ted and set in the south end of the greenhouse. A small opening was made In the glass, and through this opening one of the two stems of the plant was thrust, the open space about the stem where It passed through the glass being carefully plugged. During the rest of the winter the plant remained re-mained in the same position, the pot and one stem continuing in the warm temperature of the greenhouse, while the other stem, projecting through the glass, was exposed to the rigors of winter, with its alternate freezing and thawing. About the middle of April the out-door branch started Into normal nor-mal growth, while the indoor branch continued dormant. A modification of this experiment wns conducted at the same time with another plant. In this case the plant was set on a shelf outside the greenhouse green-house and a single branch run through the glass into the warn inter or When spring came it was the interior branch that remained dormant, all the outside out-side branches putting out leaves promptly. Thus the two experiments served to check each other. From a comparison of these two experiments It is evident that the difference dif-ference in behavior of the indoor and outdoor branches could not Have been caused by any special action of the root system, for in one experiment tne roots were inside, and in the other out. It is clear that the causes that stimulated growth in the exposed stems operated in the stem itself, not in the roots. The theory is that the cold weakens the plant cells, and by destruction in part turns the starch to sugar, thus assuring new growth. This event, it is asserted, cannot take place if the plants are protected from frost and cellular injury. A little consideration will show how important the principle of chilling is to those species of trees and shrubs which are subjected each year to several sev-eral months of freezing weather. If they are so constituted as to start into in-to growth as easily in the warm days of late fall as they do In the warm days of early spring, many species would come into flowers and leaf in those warm autumn spells that we call Indian summer, and the stored food that the plant required for Its normal vigorous growth in the following follow-ing spring would be wasted in a burst of new autumn growth, which would be killed by the first heavy freezes and would be followed by a winter of weakness and probable death. But when two or three months of . chilling are necessary before a newly new-ly dormant plant will respond to the , usual effect of warmth, such plants . are protected against the dangers of growth in Indian summer. It Is prob-. prob-. able that all our native trees and shrubs afe thus protected. Anyone may make a simple and Instructive In-structive experiment in the fall and winter with such early spring bloomers bloom-ers as alder, hazelnut, pussy willow, yellow bush jasmine, forsythia, Japanese Jap-anese quince, peach and plum. In mid-autumn bring into your living room nnd set in water freshly cut, dormant, leafless branches of these plants. They will not bloom. At Intervals In-tervals of a few weeks during the late autumn and winter try the same experiment ex-periment again. It .will be found that the branches cut at later dates will come into bloom under this treatment. They will not do so, however, until the expiration of the period chilling appropriate to the various kinds of plants Included In the experiment. It might bo argued thut In the tropics trop-ics there Is no chilling weather, yet that trees and shrubs spring Into growth after the dormant period of the dry season just as they do in temperate tem-perate climes after the dormant period of winter. The critical scientific man will therefore ask, "Are there not other oth-er agencies than chilling which will start dormant trees and shrubs into growth even in our own Intitude?" It must be said in.reply that there are. And it Is worth while to consider some of these causes, for not only are they of Interest In themselves but also Instead In-stead of weakening the hvpotllesls here presented, they serve to strengthen strength-en nnd confirm it. The pruning of a long-dormant plant will often start It into growth. Girdling Gird-ling produces a similar result Notching Notch-ing the stem does the same. Rubbing the stem also starts the plant into growth. In all these examples of the stimulation of growth by injury It is conceived that the enzym, or soluble ferment, which is found In all plants and which transforms starch into sugar, su-gar, is brought into contact with the starch as - direct result of the breaking break-ing and straining of the cells, thus causing sugar to be formed and growth to begin. Tropical plants probably have various methods of coming out of their dormancy, and there is ever? reason to expect that some of them will be found to accomplish this act in the same way as our long dormant greenhouse, by the weakening of thelt cell membranes. This is in effect substantially sub-stantially identical with chilling. As a single example of the practical practi-cal application of the principle of chilling, chill-ing, it may be stated that the sciet-tlsts sciet-tlsts of the Department of Agriculture Agricul-ture in efforts to domesticate the will blueberry plant, have succeeded through the medium of hybrids, u bringing these plants into highly pi ductive bearing. They have mad; them fruit so luxuriously and abuni-antly abuni-antly that they brought returns to tt: growers at the rate of more than $l-000 $l-000 an acre. In a word, they chanjfl the blueberry from a small wild fru: the size of a pea to a fruit nlmos the size of a Concord grape, and tin: have made its culture a profitable Industry. These things they would not ha' been able to do, however, unless th;. had first worked out the principle ol chilling, an understanding of wbic was essential to their work of brewing brew-ing and propagation. Going still further, the scientists responsible re-sponsible for these improved varlf ties of blueberries hnve made the-yield, the-yield, In greenhouses, ripe blueberrle-In blueberrle-In February and March, the larger berries reaching n diameter of ovk three-quarters of an Inch. At varlois times from midsummer to autumn tt plants were placed In t 'nss fnmes orti-ficlally orti-ficlally chilled. After two or three months' chilling they were taken lot' a greenhouse nnd at once began gro" lug and flowering, whl'.e similar plants that had not been through the cliU'ln-" perlrd continued dormant In tne s.i"' greenhouse. This Is additional pnv-of pnv-of the fact that a period of chllll"':' a general requirement of norther plants. |