30 NATURE STUDY. 



woods, in dry or damp ground, it was equalh- at home; 

 and when we climbed a mountain there was the yarrow at 

 all altitudes, even at the top. To be sure, there, it was 

 checked in its pride and diminished in size, as are all al- 

 pine flowers ; for the severe conditions at a high altitude 

 demand as small a surface expansion in the plant as pos- 

 sible and Nature responds by reducing the stems of the 

 plants. 



The equisetum or horse-tail rush is a plant the children 

 love. They gather the long reed-like stems and pull them 

 to pieces at the joints. It is a flowerless plant, which pro- 

 duces in summer a cone-like spike made up of scales, 

 shield shaped, which bear on their under surfaces cases 

 containing the spores. Examined under the microscope, 

 each one of these spores is found to have curled about it 

 four slender threads, which, when the spore is damp, cling 

 closely around it, but when dry, spring back and so dis- 

 lodge the spore. 



A short time ago, on a walk, the leaves sprouting from 

 an old oak stump caught my attention, on account of their 

 bright color. I picked a small branch and noticed a clus- 

 ter of perfect little apples growing to the leaves. They 

 were silver\- white in color with a blush of red on each one. 

 I knew them to be oak-galls, aVjnormal growths made from 

 the sting of an insect. Many plants are so stung by differ- 

 ent insects, but in the case of the oak, it is usually the 

 small wasp, Cynips. The eggs of the insect are deposited 

 at the same time that the sting is made, and the surround- 

 ing tissue of the leaf or stem is stimulated into a new 

 growth. Perfect protection is thus afforded the young lar- 

 va which matures inside of the gall. 



Galls vary in size and structure. vSome of theml are 

 many celled and so accomodate many larvae. They con- 

 tain a large proportion of tannic acid and are u.sed in the 

 preparation of leather, and also in the making of inks and 



