360 



Handbook of Nature-Study 



The spiny 

 oak-ealL. 



The pointed bullet-gall 

 on oak twigs. 



A cluster 



of galls on 



midrib of 



oak leaf. 



The acorn 

 plum-gall. 



Photo by 

 L. H. Weld. 



THE GALL-DWELLERS 



He retired to his chamber, took his lamp, and summoned the genius as usual. 

 "Genius," said he, "build me a palace near the sultan's, fit for the reception of my spouse, 

 the princess; but instead of stone, let the walls be formed of massy gold and silver, laid 

 in alternate rows; and let the interstices be enriched with diamonds and emeralds. The 

 palace must have a delightful garden, planted with aromatic shrubs and plants, bearing 

 the most delicious fruits and beautiful flowers. But, in particular, let there be an 

 immense treasure of gold and silver coin. The palace, moreover, must be well provided 

 with offices, storehouses, and stables full of the finest horses, and attended by equerries, 

 grooms, and hunting equipage." By the dawn of the ensuing morning, the genius 

 presented himself to Aladdin, and said, "Sir, your palace is finished; come and see if it 

 accords with your wishes." — Arabian Nights Entertainments. 



LTHOUGH Aladdin is out of fashion, we still 

 have houses of magic that are even more 

 wonderful than that produced by his resource- 

 ful lamp. These houses are built through an 

 occult partnership between insects and plant 

 tissues ; and no one understands just how they 

 are made, although we are beginning to 

 understand a little concerning the reasons for 

 the growth. These houses are called galls 

 and are thus well named, since they grow 

 because of an irritation to the plant caused 

 by the insect. 

 There are many forms of these gall-dwellings, and they may grow upon 

 the root, branch, leaf, blossom, or fruit. The miraculous thing about 

 them is that each kind of insect builds its magical house on a certain part 

 of a certain species of tree or plant; and the house is always of a certain 

 definite form on the outside and of a certain particular pattern within. 

 Many widely differing species of insects are gall-makers; and he who is 

 skilled in gall lore knows, when he looks at the outside of the house, just' 

 what insect dwells within it. 



