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vVith the second group of injurious mites this paper has chiefly 
do. Ihe peculiar deformities to which many of them give rise 
ye placed by the earlier botanists among fungi, chiefly in the 
jera Ermeum and Phyllerium, and the disease at that time was 
led ermiosis. In 1737 a French naturalist, Reaumur, found in 
. abnormal growth on the linden, a minute worm-like animal 
icli he thought gave rise to the abnormal formations on the 
ve s. This animal was determined, by a later French entomolo- 
t (Duges) to be a mite, and it received from him the geneiic name 
ytoptus, from its plant-infesting habits. Since then, others of 
se growths have been traced to their causes, and at present a 
: g hst of plants may be given, each of which has its peculiar 
ytoptus. The growths are now called by specialists, ceciclii, or 
ij re exactly, acaro-cecidii. 
m 
idhe growths to which the Phytopti give rise are not always what 
1 fl-d be called galls \ and in some cases they do not produce growths 
iny kind, but live in the buds in such numbers that the latter 
er develop, but remain blackened and swollen. Besides swellings 
! ^ .leaf . substance called gails, the attacks of some of these 
fees give rise to dense mats of twisted hairs on the under side of 
! r es, and in the midst of these groves the mites live and propo- 
3 . These hairs differ very little in character from the ordinary 
rs of the plant, being sometimes single and again many-celled, 
the occurrence in dense groves and the frequent strange forms 
ch they assume will ordinarily distinguish them from the normal 
s of the plant. Some of the forms of these hairs may be worth 
: eating. A common one is what may be called club-shaped, the 
|* bem g slender towards the leaf, and expanding slightly towards 
| extremity. Others of the hairs expand more abruptly outwards, 
are quite short, being thus knob-like. Occasionally one occurs 
! 1 gives off a lateral shoot, and often most of the hairs consti- 
ng a grove are irregularly twisted. The usual form is, however, 
r nearly that of the scattered hairs which may be found on other 
;<s of the piant. The patches of these hairs are at first white, 
« when old assume a rusty-brown color very like that of some of 
fungi known as rusts. At this stage few mites will be found in 
growths, the brown color of the hairs being due to their havino- 
i exhausted and dried up. 
