Sir Joseph Dalton Hooker. 



Vll 



Europe on that grand subject, that almost keystone of the laws of creation, 

 Geographical Distribution " (L.L., vol. 1, p. 336). If his unsuccess was a 

 personal disappointment, it was a gain to science, and he was immediately 

 (1846) appointed Botanist to the Geological Survey, in succession to Henfrey. 



Hooker records in 1853 that Darwin " directed my earliest studies in the 

 subject of the distribution and variation of species " ('Fl. K Z.,' p. xxii). One 

 of the first tasks he imposed upon him was the study of the flora of the 

 Galapagos, which was to play so important a part in the development of 

 Darwin's theory. For what it and its fauna impressed upon him was the 

 fact of divergence due to variation and isolation. Hooker made the plants, in 

 1847, the subject of two papers in the ' Transactions of the Linnean Society.' 

 In the second, he indicates two important principles : the struggle for 

 existence and the effect of isolation, the latter being really a corollary from 

 the former. If the species from the several islands were united in one area, 

 " the strife with its neighbours .... would terminate in a few replacing the 

 many " (' Linn. Trans.,' vol. 20, p. 259). Hence it follows that " the first steps 

 towards ensuring the continuance of many species in a given area are to 

 isolate them." As to the crucial problem, the affinity but divergence of the 

 species in the several islands, he contents himself with saying that it " is a 

 mystery which it is my object to portray, but not to explain." That he left 

 to Darwin, whose solution he knew. But that he had some opinion of his 

 own on the subject is evident, as in the same year he instances the Galapagos 

 as a case " where time, the required element for developing such species as 

 are the offspring of variation, has been granted" ('Fl. Ant.,' p. 217). 



Hooker's palteontological work was more or less official, and therefore 

 practically limited to the subjects submitted to him. These were discussed 

 in numerous papers up to 1855, after which fossil botany ceased to occupy 

 him. Prof. Seward has kindly examined them in detail, and, surveying them 

 as a whole, finds that " Hooker's contributions to Palaeobotany have been the 

 means not only of throwing new light on certain extinct types, but, by their 

 eminently philosophical spirit, of setting a high standard in a subject which 

 has suffered greatly from unscientific treatment at the hands of less cautious 

 contributors, insufficiently trained to appreciate the difficulties of palseo- 

 botanical research." In this sense Hooker was a pioneer in the application 

 to such research of a rigid scientific method, which is peculiarly necessary in 

 drawing conclusions from data which are necessarily fragmentary. In three 

 cases he succeeded in establishing new and important facts. The results of 

 an examination (1848) of some remarkable specimens of Stigmaria, the root 

 of Lepidodendron and- Sigiliaria, were long accepted in text-books. They 

 have, however, since been modified by Williamson's discovery that what 

 Hooker had worked upon was not the actual structure but an inverse cast of 

 it. This, however, did not affect the fact established by him, that the rootlets 

 derive their vascular supply from the main axis. In the same year 

 he threw much light on the morphology and anatomy of Lepidostrobus, the 

 strobilus of Lepidodendron, and Eobert Brown in 1851 records the interesting 



