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THE AMERICAN NATURALIST [Vol. LII 



At its height the Knoppern yields from 45 to 50 per 

 cent, of tannin. 



Cynips koixaei Hartig 

 The Devonshire gall is produced by Cynips kollari on 

 Quercus avellance-formis, Quercus fastigiata, Quercus 

 h um Wis, Quercus ilex, Quercus lusitcmica and varieties, 

 Quercus mirbeckii, Quercus mongolica, Quercus peduncu- 

 lata and varieties, Quercus pubescens, Quercus pseudocegi- 

 lops, Quercus rubra, Qui reus sessUifiora, Quercus suber 

 and Quercus toza. It occurs in middle and southern 

 Europe, North Africa, Asia Minor, and was introduced 

 into England from the continent early in the nineteenth 

 century. It attracted much attention because of its rapid 

 spread, but the interest in it seems to have been confined 

 to England, as no important reference to it has been found 

 elsewhere. 



Attention was first drawn to this gall in England, when 

 it became so abundant that the extermination of the oak 

 forests seemed threatened by it. At that time, about 

 1858, many notices concerning it appeared in which fear 

 was expressed that it would do irreparable injury to the 

 oaks. But the damage done by it was of no great moment 

 and when the gall was studied it was found to have some 

 tanning and dyeing properties, and to be useful in making 

 an excellent ink. 



Many analyses were made of this gall in which varying 

 amounts of tannin were accredited to it. The following 

 was made in 1869 by Watson Smith : 



Tannic acid 26.71 



Gallic acid Traces only 



Woody fiber 47.88 



Moisture 20.61 



Coloring and loss 4.80 



iooToo 



Rhodites eos.e Linnaeus 

 The Bedeguar of the rose, the gall produced by Rhodites 

 roscc Linnaeus, occurs throughout Europe and in western 



