CONSIDERATIONS OF ABNORMAL GALL-GROWTH. 85 



We see the two parts (of course only speaking of the 

 species of galls where two parts exist) can carry on life each 

 without the other, and that there is in some cases a chemical 

 difference is shown by galls of A. radicis changing colour in 

 the general mass when cut by a steel knife, whilst the section 

 of the cells continues white. In the same species of gall we 

 have the large cellular mass ibrcing itself rapidly up through 

 the bark from the cambium region beneath, during the flow of 

 sap in the spring, whilst the single-celled form placed in the 

 substance of the young bark simply exists in the shape of 

 detached specimens, this difference no way proving difference 

 in the gall, as may be shown in the cells of the woolly-gall, 

 where some exist single, some double, some in indivisible 

 clusters. In the artichoke-gall we have frequently an 

 abortive form, with the gall-chamber missing, in which the 

 larval action appears to have been interrupted before the 

 formation of the cell, so as only to have given rise to what is 

 botanically an abortive shoot, with its longitudinal growth 

 checked, but the adventitious buds thrown into action in the 

 form of the stunted leaves which compose the scales. 



[."irr. 3. AnDIUCLTS INFLATOK. 



In Andricifs injlator we have the inner chamber containing 

 the gall insect, with a clear illustration of simply modified 

 vegetable action in the surrounding shortened shoot, 

 giving rise to its numerous sprays; and in the specimen, 

 whether we consider the two lower cells those of A. injiator 

 or A. curvntof, we have an example of the gall-chamber 

 existing without its characteristic involucral development, 

 whilst above is a specimen which, when fresh, must 

 have been abnormally swollen even for A. curvator, and from 

 which there appears no reason botanically why another gall 



