122 NOTICES OF BOOKS AND MEMOIRS. 



Protections against unfavourable weather are — runners (which 

 support plants against overweight of snow in alpine and polar 

 regions, and by admitting of a complete covering of snow are 

 enabled to resist the otherwise fatal effects of frost) ; aerial roots — 

 props against land- storms and dash of the waves ; gregarious habit 

 lessening the force of the wind, a result accomplished also by the 

 horizontal position of the branches, by development of small scaly 

 leaves, and by possession of leafy crowns, deep roots and strong or 

 slim stems ; hauy clothing, which protects against cold, rain and 

 undue transpiration, and also intercepts and retains ram and dew ; 

 irritability to light or touch ; possession of a waxy outer layer and 

 of a strong cuticle ; a thick sap which, owing to the hygroscopic 

 property of its solid constituents, keeps the cu'culation active during 

 the period of greatest sun-heat and the dry season ; ethereal oils 

 which, gradually evaporatmg, produce resin, a layer of which, 

 accumulating on the evaporating surfaces, lessens the amount of 

 transph'ation ; the thick sap of plants growing in deserts, where 

 the difference between the temperature of day and night is very 

 great, containing amorphous substances which are bad conductors 

 of heat, i^rotects them against injury from the daily great variations 

 of temperature ; phyllodes, and leaves occupying the position of 

 phyllodes, being less trans^ju-able, are adaptations to a diy climate ; 

 presence of corky tissues which protect against fi'ost, &c. ; absence 

 of stomata, which in some cases prevents entry of thawing snow ; 

 thickened roots, &c., which are stores of nutriment and water, 

 and i^reserve life during times of di'ought ; besides the many 

 arangements by which the reproductive organs are protected from 

 rain, dew and Avind. 



The author shows ready command of all recent information on 

 vegetable function, such as the intoxicating properties of grasses, 

 and the reci^jrocal relations between ants and their plant-homes. 

 He is a strong advocate for fertilization by means of dew, in 

 the case of spicate grasses and of lowly small-flowered herbs, 

 such as Saylna and liadiola. He concludes that, as a general 

 rule, scented fruits fall and attract gnawmg insects, while un- 

 scented ones are brightly coloured and attractive to bu'ds. His 

 view of the origin of cleistogamy agrees in some respects with 

 Mr. Darwin's, and he remarks with regard to it that wheat and 

 barley are cleistogamous only in cold regions, and that Oryza 

 clandestina is in the same condition only during cold summers : he 

 also thinks that liabihty to have the nectar stolen without resulting 

 pollination may be a state of things from which cleistogamy may 

 result. Probably none who have thought much about the phylo- 

 geny of vegetation will disagree with the conclusion that the 

 gramineous type is one of degradation, though they may be un- 

 willing to subscribe to the view that differentiation of the forms 

 has occurred for the most part in temperate regions, and that the 

 lowly grasses found in the tropics are migrants of the glacial 

 period. It is worthy of mention, too, that this author ranges him- 

 self on the side of those who think that Gymnosperms and Mono- 

 cotyledons have originated near to but not from one another. The 



