3° 6 THE NATURE-STUDY REVIEW [a :9 _ DECi> Igc6 



on compounds in the soil. The soil, instead of becoming poorer, 

 becomes richer year by year. 



In the laboratory, the students make experiments and see that 

 lupins grown in food solutions develop tubercles when brought into 

 contact with tubercles on other lupins, and these flourish in food 

 solution containing no nitrates, although (as the girls have already 

 found out by means of other experiments) most plants without tubercles 

 cannot live unless nitrogen, in the form of some compound, is given 

 to them so that they can take it in by means of their roots. Other 

 experiments in the garden are those in connection with the food 

 made by green plants in the presence of light and carbon dioxide. 

 Tests for starch are made on leaves growing in the light, and by the 

 means of iodine, which turns starch dark blue, it is proved that green 

 leaves in the garden make starch in the light, but make no starch if 

 kept in the dark. Many of the students cut out their initials, or the 

 word "starch," or anything they like, in any material easily bent, 

 and, placing the stencil thus made over a green leaf, leave it for 

 a clay or two. The leaf is then picked, placed in alcohol to dissolve 

 out the green coloring matter, and, by means of iodine, it is proved 

 that the part to which the light had access has produced starch, but 

 the covered part, to which the light did not have access, has not 

 produced starch. For example: when the stencil "starch"' is used, 

 the "starch" comes out in dark blue letters on a yellow background. 



In the autumn, the girls generally study fruits and the various 

 methods of seed dispersal; and when they return after the long hoi - 

 days, an excellent introduction to the subject is at hand. When first 

 the girls, after their absence, look at their gardens, they find many 

 plants which were never put there, and are certainly not in their 

 right places. The question arises: "How did these plants come 

 here?" and this leads the girls to see if there is anything in the form- 

 ation of the fruit or seed which would fit it for being carried to a 

 distance. They find that in some cases, as in that of the dande- 

 lion, the fruit is provided with a parachute which enables it to be 

 carried easily by the wind. In other cases, as "burrs,'' the fruit is 

 especially adapted for dispersal by animals. The fruit becomes 

 attached to the animal by means of hooks, and is carried from one 

 place to another until it drops off. 



Other fruits, again, like those of the lime, sycamore, and maple, 

 have wings which enable the wind to carry them. In some cases, as 

 balsam, the fruit bursts with a loud noise and throws out the seeds 



