60 NOTICES OF BOOKS. 



This article is followed by anothevj full of valuable comparative 

 observations on the amount of peculiar and widely dispersed species 

 taken from many local Floras. The author next proceeds to inquire 

 into the areas occupied by species in relation to the families to 

 which they belong ; thus^ comparing South Africa with France, 44 

 per cent, of the African Chenopodiacece are common to France, and 

 only 0'3 per cent, of the Compositce; whilst conversely, only 24 per 

 cent, of the French Chenopodiacece, and 0*6 per cent, of the French 

 Compo^itiBy are found in South Africa. The next succeeding article, 

 on the areas occupied by species in relation to the localities they 

 affectj he finds to be capable of much greater illustration ; thus the 

 general dispersion of fresh-water plants, marine plants, etc., is univer- 

 sally known, and on these and many similar facts M, de CandoUe 

 adduces a multitude of observations and of curious exceptions. 



In an article on the relative magnitude of the areas occupied by 

 annual, biennial, etc., plants, and on great or small plants, M. de Can- 

 doUe states that the species of small Phsenogamic plants occupy larger 

 areas than of great, and that the same remark may be extended to the 

 • whole vegetable kingdom. 



The question of the means of dispersion is naturally suggested by 

 these inquiries. Some of the results here given are extremely striking, 

 and quite opposed to our popular notions of adaptability and final 

 causes ; thus, that the pappus and other appendages to fruits is given 

 to aid dispersion is universally believed, but if it be so, how startling 

 are the facts, that of six large families, each containing a large number 

 of species whose seeds have aids to dispersion, and also a large 

 number of species whose seeds have none, those whose seeds have 

 none are more widely dispersed than the others; these families are 

 Ranuncidac€(je^ Rosacea^ MalpigJiiacet^ ^ Sapindacece^ Combretacece ^ and 

 Composite. On the other hand, plants with numerous and small seeds 

 are more widely dispersed than others. 



The observations on the area occupied by species, compared with the 

 power in their seeds of retaining their vitality, has great interest at 

 present, now that the question of seeds retaining their vitality after 

 being long buried in the soil is demanding a complete re-investigation. 

 In one experiment of M. de CandoUe's, the seeds of 368 species were 

 preserved for 15 years, when 20 of each were sown; of 10 MalvacecB^ 



r 



5 germinated; of 45 Leguminosa^, 9 ; of 30 Labialea, 16; whilst of 



