39 



REVIEWS. 



Aeltere nnd nene Benhachtiuigen ilber Phytopto-Cecidien. 

 By Dr. F. A. VV. Thomas. Halle-on-Saale. 1877. 



This short pamphlet, of ' Former and Recent Observations 

 on Phytoptns Galls,' gives in its fifty-nine pages much 

 information of value. It is reprinted from the ' Zeitschrift 

 Gesam. Naturw.' (vol. xlix., 1877), and is accompanied by 

 one plate. It comprises a chronological sketch of the litera- 

 ture of the subject from the first recorded observations to the 

 end of 1870; also some notes on gall structure, and on 

 Beyerinck's classification of the mite galls. These are 

 followed by descriptions of new or little known Pliytoptus 

 galls, in continuation of the author's previous publications in 

 the 'Nova Acta' of the Leopold-Charles Academy. 



The first recorded observations of mite-galls appear, 

 according to Hardy, to have been those of the brothers 

 Bauhin, on the silky-haired growths of Thynnis serpyllum. 

 The subject is then traced onwards, — through Malpighi's 

 observations on the vine Ervieum, Tourneforl's conjecture 

 in 1698 as to the cause of the diseased growth lying in insect 

 puncture, Reaumur's descriptions of the leaf-galls of the 

 lime and sycamore (still without any knowledge of the tenants 

 and immediate cause), and Vallot's numerous discoveries and 

 observations, — to the period when, through Turpin's examin- 

 ation, the formation of these galls was found to be attributable 

 to mite agency. 



The history of the gradual dawn of certain light on the 

 subject is much the history of the experience of each 

 original observer of modern days. There is in either case 

 the attention attracted by the diseased growth (the "felts" 

 of the early botanists), the gradual discovery of the Acarid 

 presence, and the long investigation requisite for proof as to 

 which of the various tenants is the fundamental cause of the 

 diseased structure. This history is necessarily full of refer- 

 ences (which are fully given by Dr. Thomas) to the publica- 

 tions of continental and American observers, as well as of our 

 own country. 



Descriptions and notes on structure of previously unknown 

 or little known galls occupy about half the pamphlet; these 

 in many cases occurring on species commonly found with us, 

 €.(j. of Veronica, Slellaria, Cerasliiim, &c., so as to make the 

 observations with the previously published notes available as 



