100 The Galls of Essex; a Contribution to a 



supposed to consist of some acid injection into the plant- 

 tissues, at the time of oviposition, by the parent insect. 

 It may well be thought that the Cynipidse sting plants in a 

 way similar to that in which the Aculeate Hymenoptera 

 (ants, bees, wasps, &c.) operate upon animals, and which is 

 so often painfully patent to ourselves ; even the gall-gnats 

 (Cecidomyidfe) may be similarly accredited with a kind of 

 stinging power without much stretch of imagination, when 

 reasoning from analogies. But we can hardly suppose many 

 of these growths to be due to the stings of the various moths, 

 beetles, plant-lice (Aphides), bugs, and especially mites, 

 which are known to produce them. Scientifically also, the 

 theory of a special "gallic" poison injected by the mother 

 gall-maker cannot stand. I am sorry to see that Sir James 

 Paget should foster this opinion, when he remarks : — 

 "We find hundreds of difi'erent forms of galls, and we may 

 be nearly sure that there are as many kinds of morbid 

 poisons produced by the gall-insects, each form answering to 

 a difi'erent virus." ^ Mr. G. B. Buckton also writes, "It may 

 be noted that the injection of acrid or other juices into living 

 vegetable tissue by Hemiptera and other insects produces on 

 plants phenonema very similar to inflammation in animal 

 organisms. Vessels become turgid, cell- walls become thick- 

 ened, and abnormal growths (in vegetables often elegant 

 instead of monstrous) take the place of simple structures."® 



In a paper read before the Linnean Society on January 

 21st, 1875, Dr. W. Ainslie Hollis fully examined the question 

 of the causative formation of galls. To this memoh- I am 

 indebted for some of the following views and opinions of the 

 older writers. 



Zoology and Botany as sciences may reasonably be said to 

 commence with Linne. It will be quite useless to examine 

 further back, although folk-lore is very entertaining and the 



5 ' An Address on Elemental Pathology, delivered in the Pathological 

 Section of the British Medical Association, at the annual meeting in 

 Cambridge, August, 1880.' By Sir James Paget. P. 23. London, 1880. 

 Also the 'Lancet,' October 23rd, 1880, p. 646. 



*5 ' Monograph of the British Aphides.' By George Bowdler Buckton, 

 F.K.S., F.L.S., &c. London (Kay Society), vol. iii., p. 85 ; 1881. 



