258 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of her knowledge for " characters " of the genus, the section and 

 its various subdivisions. 



For the benefit of the writers of popular text-books who do not 

 seem to study systematic works or special memoirs, it may be remarked 

 that Mrs. Gregory once more alludes to her proof that the Sweet 

 Violet is not wholly dependent on its cleistogene flowers for the 

 production of seed. The production of the two types of blossom 

 is shown (p. 48) to be largely a question of sunshine or shade. 



We could wish that it had been possible to print the body of the 

 work on less weighty paper. 



" Hampstead Heath : its Geology and Natural History." 

 Prepared under the auspices of the Hampstead Scientific Society. 

 328 pp., with 3 maps and 11 plates. (T. Fisher Unwin.) 10s. 6d. net. 



A pleasant, healthy, picturesque, and most accessible suburb, 

 Hampstead has had an interesting and varied list of distinguished 

 residents, artists, poets, and men and women of letters, with the result 

 that quite an extensive series of works has appeared dealing with 

 its history and associations. As the bit of unspoilt country nearest 

 to the heart of the City, it has naturally also been at all periods 

 a favourite resort of lovers of Nature, from Thomas Johnson and 

 his fellow apothecaries who drew up the list of plants on Ericetum 

 Hamstedianum in 1629, to Samuel Pickwick, Esq., G.C.M.P.C., who, 

 on May 12, 1827, communicated his "Speculations on the Source 

 of the Hampstead Ponds, with some Observations on the Theory of 

 Tittlebats," to the Club that bore his name. Nor have their researches 

 gone unrecorded. Park's work in 1814 was entitled " Topography 

 and Natural History," and the late Mr. Lobley's volume of 1894 was 

 mainly occupied with the physical, rather than with the antiquarian, 

 side of the subject. At the same time it was a most laudable determina- 

 tion on the part of the members of the Hampstead Scientific Society, 

 when it was founded a dozen years ago, to prepare, by that co-operation 

 which alone can make such projects uniformly successful, a survey 

 of the Natural History of their area. That area — " within a radius of 

 three miles from the Flagstaff on the summit of Hampstead Heath " 

 — is, it is true, an artificial one. It includes, as Mr. Rudler points 

 out in his excellent geological chapter, considerable areas of London 

 Clay and Boulder Clay, which is often chalky, though these are not 

 included in Mr. Tansley's ecological survey of the vegetation, a survey 

 which, for the Heath itself, is remarkably thorough. Mr. Tansley's 

 chapter and that by Mr. Hugh Boyd Watt, on the trees and shrubs 

 <?f the district, give an admirable picture of the present state of the 

 area from the botanical side, the latter including cultivated trees, 

 many of which, especially those at Ken Wood, are of considerable 

 interest. We notice that Mr. Watt enumerates some 190 kinds. The 

 chapter on Flowering Plants other than trees strikes us as rather 

 sketchy ; and, though there are allusions to extinctions and intro- 

 ductions, it seems to us that an opportunity has been lost of placing 



