Five experiments were conducted to explore how the character of the retention interval affected event-based prospective memory. According to the canons of retrospective memory, prospective performance should have been worse with increasing delays between intention formation and the time it was appropriate to complete an action. That result did not occur. Rather, prospective memory was better with increasing retention intervals in Experiments 1A, 1B, and 3. In manipulating the nature of the retention interval, the authors found that there were independent contributions of retention interval length and the number of intervening activities, with more activities leading to better prospective memory (Experiments 2 and 3). The identical retention intervals did not improve retrospective memory in Experiment 4. Theoretical explanations for these dissociations between prospective and retrospective memory are considered.

No abstract

HISTORICAL AND INTRODUCTORY 19 estimated, and before he had finished, the essential facts of plant nutrition were settled and the lines were laid down along which scientific manuring was to be developed. The water cultures of Knop and other plant physiologists showed conclusively that potassium, magnesium, calcium, iron, phosphorus, along with sulphur, carbon, nitrogen, hydrogen, and oxygen are all necessary for plant life. The list differs from Liebig's only in the addition of iron and the withdrawal of silica; but even silica, although not strictly essential, is advantageous to cereals.In two directions, however, the controversies went on for many years. Farmers were slow to believe that "chemical manures" could ever do more than stimulate the crop, and declared they must ultimately exhaust the ground. The Rothamsted plots falsified this prediction ; manured year after year with the same substances and sown always with the same crops, they even now, after sixty years of chemical manuring, continue to produce good crops, although secondary effects have sometimes set in. In France the great missionary was Georges Ville, whose lectures were given at the experimental farm at Vincennes during 1867 and 1874-5 (288).He went even further than Lawes and Gilbert, and maintained that artificial manures were not only more remunerative than dung, but were the only way of keeping up fertility. In recommending mixtures of salts for manure he was not guyded by ash analysis but by field trials. For each crop one of the four constituents, nitrogen compounds, phosphates, lime, and potassium compounds (he did not consider it necessary to add any others to his manures) was found by trial to be more wanted than the others and was therefore called the " dominant " constituent. Thus for wheat he obtained the following results, and therefore concluded that on his soil wheat required a good supply of nitrogen, less phosphate, and

When soil is partially sterilised, either by heat or by volatile antiseptics like carbou disulphide, toluene, etc., it becomes more productive and capable of yielding larger crops. The effect of heat was discovered incidentally about 25 years ago by the early soil bacteriologists; the action of carbon disulphide was first noticed somewhat later by a vine grower who had used it to kill phylloxera. Both cases have since been studied by several investigators, notably Koch and Hiltner and Störiner; a paper was also recently published by one of us in which it was shown that the property is a general one, holding for all the soils and volatile antiseptics examined and for all the plants, excepting those of the leguminous order. Thus when a soil had been heated to 95° C. it produced two, three, or sometimes four times as much crop as a portion of the soil which had not been heated, whilst treatment with volatile antiseptics led to an increase in crop varying between 20 and 50 per cent.

SOIL CONDITIONS ANb PLANT GkoWTtt Helmorit considered he had found it in water, and thus records his famous Brussels experiment (132). "I took an earthen vessel in which I put 200 pounds of soil dried in an oven, then I moistened with rain water and pressed hard into it a shoot of willow weighing 5 pounds. After exactly five years the tree that had grown up weighed 169 pounds and about 3 ounces. But the vessel had never received anything but rain water or distilled water to moisten the soil when this was necessary, and it remained full of soil which was still tightly packed, and, lest any dust from outside should get into the soil, it was covered with a sheet of iron coated with tin but perforated with many holes. I did not take the weight of the leaves that fell in the autumn. In the end I dried the soil once more and got the same 200 pounds that I started with, less about two ounces. Therefore the