REVIEWS AND NOTICES OF BOOKS. 169 



diseases. In every case the description is poor, and at the 

 outset he makes inexact statements regarding the pine beetle. 

 An entomologist would not always see eye to eye with the 

 author when he states that this beetle, after tunnelling in the 

 shoot, makes its exit at the terminal bud. Nor would he agree 

 that the insect is so wary that great care must be exercised in 

 collecting the attacked shoots lest the creatures escape. In 

 any case, the collection and burning of these shoots would be 

 tedious work of no great utility in exterminating the insect. 

 Of more benefit for reducing the numbers of this and other 

 insects is, as the author insists, the removal of dead and dying 

 wood. 



Although there is a considerable store of information in this 

 book, the reviewer is of the opinion that there is still room for 

 a. first-class work on the subject. M. 



The History of the London Plane. By A. Henry and M. G. 

 Flood. Proc. Roy. Irish Acad., xxxv. Section B., No. 2, 

 1919. 



The merits of the London Plane — Platanus acerifolia — for 

 town-planting are too well known and too widely acknowledged 

 to need recapitulation. Its origin has frequently been debated, 

 and in this recently published article, by Professor Henry and 

 Miss Flood, we are provided with a satisfactory account of its 

 hybrid nature. 



After a brief account of hybrid characteristics possessed by 

 the London Plane, Professor Henry gives evidence for conclud- 

 ing that the tree was raised first at the Oxford Botanic Garden 

 not later than 1670. This date corresponds well with the age 

 of the famous Ely Plane planted by Bishop Gunning between 

 1674 and 1684. The characters of the genus are fully discussed, 

 with numerous notes on reliable characters for delimiting the 

 plants. One of these characters is a coefficient of lobing, 

 which, from the figures tabulated, brings out in a very marked 

 degree a difference between the two parents — P. occidentalis and 

 P. orientalis — and also shows how some of the hybrids of the 

 second generation approach one or other of the parents, and 

 some are intermediate. 



Full descriptions are given of the two parents, of the hybrid 

 of the first generation — P. acerifolia — and of six hybrids which 



