122 FRUIT CULTURE UNDER GLASS. 



and cuniform, have a lineal areole on the larger basilary half of 

 their outer edge ; and this is enclosed in an interior ' nervure,' 

 which answers, I suppose, to the radial muscle. One single ob- 

 lique nervure (or corneous division) is detached from this last, and 

 reaches to the inner edge. Two other lines start from the end of 

 the wing, and, becoming narrower as they proceed, advance to- 

 wards the oblique nervure, but end before reaching it. These are 

 not, perhaps, nervures, but rather folds, for I have observed them 

 absent. 



" The inferior wings, both narrower and much shorter, have a 

 marginal nervure running from the base to the middle, but it 

 loses itself in a gentle protuberance, which the wing shows in this 

 place ; a radial nervure runs parallel to the first, and disappears 

 before it reaches the same spot. 



"The eyes, black and (relatively) very large, are irregularly 

 globular, with marked conical nipples ; their surface is gran- 

 ular, but a pointed depression is observed in the centre of each 

 glandule. A round eye-shaped spot occupies the centre of the 

 forehead. 



" Among fifteen winged specimens of the Phylloxera which have 

 come under my notice, not one has presented any sexual differ- 

 ence. Almost all of them laid two or three eggs, and their death 

 (which happened soon after) may have been caused by their 

 imprisonment in the bottles. Their eggs resembled those of the 

 wingless Phylloxera, and though they were only two or three in 

 number, they completely filled the abdomen of the mother. 

 They were easily seen by placing the insect under the microscope. 

 I do not know how long the eggs remain before they are hatched, 

 or if they always produce the winged form of the insect. It is 

 probable that these winged individuals serve for the transporta- 

 tion of this insect plague to a distance ; not that their wings 

 would serve them for a rapid flight — they are too inactive, they 

 move them very little, and in rising from the ground their hori- 

 zontal position is preserved. My observations were, however, 

 made under very unfavourable conditions, the insect being in a 

 state of captivity ; but I suppose that even in a natural state the 

 wind is the principal agent for the dispersion of the Phylloxera, as 

 it is for many of the insect tribe. In any case, the discovery of 

 this form of the Phylloxera provided with wings, and evidently 

 fitted for an aerial life, is sufficient to explain the hitherto embar- 

 rassing fact of the rapid spread of this vine-plague. As to the 



