184 The Phytoptus of the Vine. By Prof. Giovanni Briosi. 
and angles. ‘They are unicellular, that is, not presenting divisions, 
of which I at least saw none. Landois, on the contrary, found 
them to be formed of a row of elongated cells, which, to my mind, 
seems a mistake; and fig. 7 of his plate xxxi.* must probably 
have been taken from a normal hair of the vine (just as one of the 
hairs of my Fig. 14, which owing to a lithographic error in some 
plates doesnot reach out of the parenchyma), and not one of those 
pathological hairs of which we are speaking. 
These hairs contain a granulated transparent protoplasm, 
colourless or slightly yellowish when young, and more or less 
opaque or yellowish-brown when old. ‘Towards their base there is 
almost invariably found (toward the end of summer) an abundant 
quantity of starch, in form of very fine granules, similar to that 
gathered by me in the vessels of the higher plants. 
Now and then (not always, as Landois says) I also found small - 
crystals in the hairs, but not in the needle form of the raphides, so 
abundant in almost all the normal textures of the vine. 
These hair crystals are in such small quantity that it does not 
bear out what Landois says of the great waste of tartrate of potash 
caused by it. The same may be said of the chlorophyll, which I 
found very rarely even in the young hairs, where, on the other 
hand, he found it in abundance. Starch I found often abundant in 
the primary parenchymic strata lying beneath the hairs, which 
unusual accumulation of material in those cells is due to the 
abnormal and extraordinary development of organic substance 
required for the formation of the hairs. The texture of the parts 
of the leaf corresponding with the galls (harder than the surround- . 
ing healthy one) is seen more or less changed; the protoplasma of 
the cells frequently lost its transparency and became dark, either 
orange or brown. . 
These changes extend frequently, with various interruptions, 
throughout the thickness of the lamina up to the cellular stratum, 
which is bordered off by the opposite side of the leaf (g, Fig. 14). 
The plant loses, therefore, not only a considerable quantity of 
plastic substance which produces the pathological texture, but also 
organs which should produce this matter, grains of chlorophyll, of 
which the cells, whose protoplasm changes, are full; and it is easily 
understood that the harm done to the respiration organs must be 
hardly less than that done at the same time to the assimilation ones. 
The raising of the texture towards the upper side of the 
leaf, that is, on the opposite one to the wounded spot, Thomas + 
* Landois, Eine Milbe (Phytoptus vitis), &c., see Publications. 
+ He says, verbatim: “ Der Intracellulardruck wird dadurch einseitig vermindert 
werden und muss folglich eine Riichwirkung ausiiben. Der nicht compensirte Druck, 
welchen der fliissige Zelleninhalt auf die der ausgesogenen Stelle diametral gegentiber- 
liegende Wand ausiibt, bewirkt die Forthewegung der Zelle selbst und des thr im Wege 
stehenden Theiles, der Blattspreite.’—Bot. Zeit. 1872, No. 17, p. 286. 
