Note Book VIII. Chap. 6. Note (z) — BOOK VIII.

[z] Since my penning this, I have met with the most sagacious Malpighi’s Account of Galls, &c. and find his Descriptions to be exceedingly accurate and true, having traced my self many of the Productions he hath mentioned. But I find Italy and Sicily (his Book de Gallis being published long after he was made Professor of Messina) more luxuriant in such Productions than England, at least, than the Parts about Upminster (where I live) are. For many, if not most of those about us, are taken Notice of by him, and several others besides that I never met with; although I have for many Years as critically observed all the Excrescences, and other morbid Tumors of Vegetables, as is almost possible, and do believe that few of them have escaped me.

As to the Method how those Galls and Balls are produced, the most simple, and consequently the most easy to be accounted for, is that in the Gems of Oak, which may be called Squamous-Oak-Cones, Capitula squamata, in Malpighi: Whose Description not exactly answering our English-Cones in divers Respects, I shall therefore pass his by, and shew only what I have observed my self concerning them.

These Cones are, in outward Appearance, perfectly like the Gems, only vastly bigger; and indeed they are no other than the Gems, encreased in Bigness, which naturally ought to be pushed out in Length: The Cause of which Obstruction of the Vegetation is this: Into the very Heart of the young tender Gem or Bud (which begins to be turgid in June, and to shoot towards the latter end of that Month, or beginning of the next; into this, I say) the Parent-Insect thrusts one or more Eggs, and not perhaps without some venomous Ichor therewith. This Egg soon becomes a Maggot, which eats it self a little Cell in the very Heart or Pith of the Gem, which is the Rudiment of the Branch, together with its Leaves and Fruit, as shall be hereafter shewn. The Branch being thus wholly destroyed, or at least its Vegetation being obstructed, the Sap that was to nourish it, is diverted to the remaining Parts of the Bud, which are only the scaly Teguments; which by these Means grow large and flourishing, and become a Covering to the Insect-Case, as before they were to the tender Branch and its Appendage.

The Case lying within this Cone, is at first but small, as the Maggot included in it is, but by degrees, as the Maggot increaseth, so it grows bigger, to about the Size of a large white Pease, long and round, resembling the Shape of a small Acorn.

The Insect it self, is (according to the modern Insectologers) of the Ichneumon-Fly Kind; with four Membranaceous Wings, reaching a little beyond the Body, articulated Horns, a large Thorax, bigger than the Belly; the Belly short and conical; much like the Heart of Animals: The Legs partly whitish, partly black. The Length of the Body from Head to Tail, about ²⁄₁₀ of an Inch; its Colour, a very beautiful shining Green, in some tending to a dark Copper-Colour. Figures both of the Cones, Cases, and Insects, may be seen among Malpighi’s Cuts of Galls, Tab. 13. and Tab. 20. Fig. 72. which Fig. 72. exhibits well enough some others of the Gall-Insects, but its Thorax is somewhat too short for ours.