632 ADDITIONS. 



Dr. Hooker's remarks on the limits of species, tlieir dispersion and 

 variation, are striking and instructive. He is of opinion that species 

 vary more, and are more widely diffused, than is usually supposed. 

 Hence he conceives that the number of species has been needlessly and 

 erroneously multiplied, by distinguishing the specimens which occur in 

 different places, and vary in unessential features. He says that though, 

 according to the lowest estimate of compilers, 100,000 is the common- 

 ly received number of known plants, he thinks that half that number 

 is much nearer the truth. " This," he says, " may be well conceived, 

 when it is notorious that nineteen species have been made of the Com- 

 mon Potatoe, and many more of Solanum nigrum alone. Pteris 

 aquilina has given rise to numerous book species; Vernonia cinerea of 



India to fifteen at least Many more plants are common to 



most countries than is supposed ; I have found 60 New Zealand flower- 

 ing plants and 9 Ferns to be European ones, besides inhabiting nume- 

 rous intermediate countries So long ago as 1814, Mr. Brown 



drew attention to the importance of such considerations, and gave a 

 list of 150 European plants common to Australia." 



As an example of the extent to which unessential differences may go, 

 he says (p. xvii.,) " The few remaining native Cedars of Lebanon may 

 be abnormal states of the tree which was once spread over the whole 

 of the Lebanon ; for there are now growing in England varieties of it 

 which have no existence in a wild state. Some of them closely resemble 

 the Cedars of Atlas and of the Himalayas (Deodar ;) and the absence 

 of any valid botanical differences tends to prove that all, though gene- 

 rally supposed to be different species, are one." 



Still the great majority of the species of plants in those Southern 

 regions are peculiar. "There are upwards of 100 genera, subgenera, or 

 other well marked groups of plants, entirely or nearly confined to New 

 Zealand, Australia, and extra-tropical South America. They are re- 

 presented by one or more species in two or more of those countries, 

 and thus effect a botanical relationship or affinity between them all 

 which every botanist appreciates." 



In reference to the History of Botany, I have received corrections 

 and remarks from Dr. Hooker, with which I am allowed to enrich my 

 pages. 



"P. 359. Note s . Nelumbium speciosmn, the Lotus of India. The 

 Ndunibium does not float, but raises both leaf and flower several feet 

 above the water : the Nymplioea Lotus has floating leaves. Both enter 

 largely into the symbolism of the Hindoos, and are often confounded 



