8 APPLE-ROOT BLIGHT EXCKESCEKCES DESCRlBEiy. 



roots of the Apple tree and their more slender, fibrous, and capillary 

 branches. In the single instance in which they have come under 

 my notice, the main root of the young tree was half an inch in 

 diameter, half a span below the surface, at which point it was 

 two-thirds surrounded by an excrescence two inches in length and 

 three inches in diameter and height, and connected to the root 

 by a neck much smaller than its base. (The- accompanying 

 figure is a view of the back of this excre- 

 scence, reduced to one fourth its actual 

 size, and one of the small fibrous roots, 

 with an excrescence thereon. The origi- 

 nal specimen is preserved in the Entomo- 

 logical department of the Museum of the 

 State Agricultural Society.) It is of an 

 K irregular, knobbed form. Its surface is 

 of the same yellowish-brown color as> the bark of the root, and is 

 everywhere crowded with little round elevations,.from the size of 

 a mustard seed to that of a buck shot or a small pea. On cutting 

 one of the projecting knobs, it is found to be of a very hard, 

 woody texture, and without any cavities in its center. Upon the 

 main root, between this and the surface of the earth, was a second 

 similar excrescence, but smaller ; whilst upon several of the small 

 capillary fibres were similar tubers, from the size of a pea to that 

 of a bullet. 



These excrescences are doubtless formed in much the same way 

 that galls and other morbid enlargements in the structure of vege- 

 tables are produced. The parent insect insinuates herself down- 

 wards along the siae of the root, as it would appear, at the close 

 of autumn, and there deposits her stock of eggs, and perishes. 

 TItese eggs hatch when the ground becomes warm the following 

 spring, and the young lice insert their beaks into the bark of the 

 root to extract their nourishment therefrom. Their punctures 

 produce a kind of irritation, which causes an increased flow of 

 fluids to the spot where they are located. This excessive amount 

 of sap thus diverted to this part occasions an increased growth of 

 the wood, and results in the enormous development which we 

 have witnessed. As in other cases in this family, these lice pro- 

 bably continue to multiply without any intercourse of the sexes 



