526 Chronicles of Science. [Oct., 



Mr. Bentham believes that too much stress has been laid on the 

 structural appliances for the dissemination of seeds, and too httle 

 on the external means of transportation by birds, &c. Among 

 Compositse, several species of Eclipta, Elephantojms, Anthemis, 

 and Lapsana, the fruit of which is destitute of pappus, have a 

 much more wide-spread distribution than the great majority of 

 Senecios. A large proportion, too, of the thistle-down which is 

 seen floating in the air will be found on examination to have lost its 

 seeds. It is calculated that out of every 100,000 seeds of the wild 

 foxglove, 99,999 must perish before reaching the reproductive age. 

 The usual explanation of the sudden appearance of new species in 

 localities where they were hitherto unknown, on an alteration in the 

 condition of the soil, is De Candolle's statement, " II faut done 

 regarder la couche de terre vegetale d'un pays comme un magasin 

 de graines au profit des especes indigenes." This supposition 

 appears to rest entirely on circumstantial evidence, where direct 

 evidence ought to be easily attainable. Though the seeds of plants 

 which thus suddenly appear in great quantities are often by no 

 means microscopical, as in the case of the white or Dutch clover, 

 there is no record of a single instance in which these stores have 

 been actually seen. Nor is there any satisfactory evidence that 

 seeds will retain their vitahty for any considerable length of time 

 unless kept perfectly dry. Mr. Bentham would be more disposed 

 to account for these sudden appearances by the rapid transportation 

 of seeds by birds and other means than by the ordinary theory of 

 stores buried in the ground for an indefinite period. 



F reservation of Sub-tropical Plants through the Winter. — 

 The mild winter of 1868-69, following closely on the remarkably 

 fine summer of 1868, was favourable to the preservation of half- 

 hardy plants through the winter. In the gardens of Battersea 

 Park a number of such plants and shrubs have now been preserved 

 for several winters by a covering of dry Htter or other loose non- 

 conducting material sufiiciently thick to exclude frost. Under this 

 treatment Ganna 'peruviana and expansa have been preserved for 

 two years ; Aralia papyrifera and Solanum laciniatum-elegans 

 survived last winter; while a variety of the rice-paper plant, 

 A. Sieholdi, has hved through five winters, and Echeveria secundor- 

 glauca has withstood 22° of frost. 



Sources of Copal.— Mr. Jackson, the Curator of the Museum at 

 Kew, has been investigating the sources of copal, an article well 

 known to commercial men, but the origin of which has been 

 imperfectly ascertamed by botanists. Several sorts of copal are 

 known in British trade, as the Brazilian, Indian. African, &c., the 

 product of widely difi'erent plants. Dammar, or East Indian copal, 

 is said to be the produce of Valeria indica. Dammara orientalis 

 and australis (Coniferae) also furnish copal from Moluccas and 



