An eleventh letter to Sir Joseph Banks ... on the subject of cochineal inscets, discovered at Madras / [James Anderson].

  • Anderson, James, 1738-1809
Date:
1787
Catalogue details

Licence: Public Domain Mark

Credit: An eleventh letter to Sir Joseph Banks ... on the subject of cochineal inscets, discovered at Madras / [James Anderson]. Source: Wellcome Collection.

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    On examining the beak or Rojlrum PeHorah of many of the female Phylhnthus Emblica Tnfefls, Ve found two hairs fimilar to thofe deferibed by Dodor Garden of South Carolina, andalfoa Cylindrical ftyle iflliing from the very Centre of its Apex poUelfed of Mufcular motion in all diredions, in the manner of the Tongue of fuch Reptiles as the Snake, Lizzard, Manis 5ic. The procefs of clearing off the Silk from the Infeds to prepare them for being viewed was frequently attended with the lofs of the hairs, which are by thefe means torn off, and the Lifed withdrawing its 7’ongue, nothing appeared but the RoJiru?n^ which in this Infed is a Cone, tne Apex of which is acute. On this account we placed foine young Infeds, that had been but a few days from the fhell, under ♦he Microfeope, and found on the P^oJlru7n a Filament, which was tv/ice as long as the whole In- fed, and terminated in a little Button or Knob like the Antennes of a Butterfly, and when the Infed creeped about, wc perceived the Filament dragging after it, like a Funis Umbilicalis. Taking afterwards fome of a larger fize, about quarter grown, at which period they begin to faften to the leaf, and are covered with a white Pellicle., or Farina, but have not vetbecun to fpin, w'e could not perceive any button or knob, but in place thereof found that the I ilament was Iplit at the extremity, appearing there to be two hairs. I have frequently obferved that full grown Infeds ffripped of their Silk, and put under the Microfeope for examination, have in the courfe of one night covered themfelves again with Silk, from whence it is obvious they can throw off the threads in ail diredions; but we could not perceive the particular manner in which this w'as effeded. The Seta: or Briflles mentioned in my Letter of Augufl ill, feem now to be nothing more than fnort hairs with which t\\Q Pun£iu7n Subulatum is funulhed in the fame way as the Le<^s of the infed, on all of v/hich that I have feen there are likevvife fliort hairs. You will readily perceive from the various appearances on the Puncliim Subulatum it is too minute an objed to admit certain charadters being deduded from its ftrudure ; ajid althotf^h I have now relinquilhcd every idea on this ground, I thought it might afford you fome fatisfadlon to be acquainted with the attempts I have made, to find a Ipecific cnarader independant of the Plants on which Infeds are found. That I have not been altogether without fuccefs, appears from the oviparous nature of this Infed, which may ferve as a fpecihe diftindion. I alfo expofed the Guava Coccus to a great magnifying power, and difeovered its eyes prominent and black, one on each fide immediately below the infertion of the Antennce, which I imagined might be ufed as a fpecific diftindion, but refleding on the probabilitv, that there are eyes in all female Coccus Infeds, though hitherto unobferved, and as this Infed was frequently minutely ex- amined under the Microfeope before, without making any fuch difeovery, I laid afidc the idea ; and finding