GALLS FOUND NEAR BOSTON. 61 



MEETING FOR DISCUSSION. 

 Galls Found Near Boston. 



By Miss Cora H. Clarke, of Jamaica Plain. 



In the "Encyclopaedia Britannica" we find this definition: — 

 *' "What are commonly known as Galls are vegetable deformities 

 or excrescences, and, according to Lacaze-Duthiers, comprise all 

 abnormal vegetable productions developed on plants by the 

 action of animals, more particularly by insects, whatever ma}' be 

 their form, bulk, or situation." Professor Rile}', in his interesting 

 article on the subject in Johnson's Encyclopaedia, says that the 

 name should not be applied, as it sometimes is, to those plant 

 swellings and nodosities caused by the punctures of insects which 

 always dwell exposed thereon, the difference between a gall and 

 a mere swelling being that the architect of the former is hidden 

 from view, and that of the latter always exposed. 



Fungous growths in plants often produce swellings and mon- 

 strosities which might be mistaken for true galls and in some 

 cases are called galls, and some galls much resemble fruits, and 

 those unfamiliar with botany might take them for the fruit of the 

 plant upon which they grow. 



The first question that occurs to us on looking at a gall, is 

 •"How can the insect make the gall?" The statement was 

 formerly made that the gall was caused by a poison which the 

 mother insect injected into the wound when she laid the egg, and 

 this Dr. Adler has found to be true in regard to the galls produced 

 by saw-flies. He has carefully watched the gall growth of one 

 species, and thus describes it : — 



" The Saw-fly (Nematus) with its delicate saw-shaped sting, 

 makes an incision in the tender little leaf of the terminal shoot of 

 JSalix amygdalina, and shoves its egg into the wound ; at the 

 same time, something flows into the wound from a glandular 

 secretion of the saw-fly. A few hours after the egg is laid, the 

 surface of the leaf takes on another appearance, and there begins 

 a new formation of cells, which leads to a limited thickening of 

 the leaf surface ; in about two weeks the bean-shaped, greenish 

 red gall is fully grown ; if one opens it at this time, the egg still 

 lies in the small central cavity, the development of the embryo 



