ASSISTANT AT KEW 353 
Thus at length his own and his father's highest hopes were 
realised. Till Sir William's death ten years later, leaving his 
son and assistant obviously marked out as successor to the 
Directorship, father and son were settled together at the Mecca 
of botany they had created, united by strong affection as well 
as by a common work. 
The culminating point of Hooker's scientific work during 
the decade is the Introductory Essay to the Flora of Tasmania, 
' which in itself would have made Hooker famous,' writes 
Professor Bower.i This was published in 1859, just before 
the * Origin of Species ' appeared. Six years earlier he had 
published the corresponding Introductory Essay to the Flora 
of New Zealand. The difference between the guiding con- 
ceptions of these Essays, one in the middle, the other at the 
end of his first great period of systematic work, is a measure 
of the writer's advance in scientific theory, his long-standing 
dissatisfaction with the older view of fixity of species finding 
appeasement in the practical utility of the theory that species 
originate in variation. 
He had long been the confidant of Darwin's views ; had 
discussed and debated them with his old friend, providing 
botanical information, offering criticisms, citing instances 
and pointing out difficulties, suggesting his own solutions to 
problems which had vexed him ever more insistently as he 
more fully reahsed the fluidity of species, and the difficulty 
of estabHshing ' specific types,' — those abstract definitions, to 
which individual specimens should be referred, being as hopeless 
as the bed of Procrustes. On the main Hnes, at least, he was 
approaching conviction. The new theory, privately discussed, 
threw light on his own work if he was not yet, in the earlier 
fifties, persuaded of all its details ; and he felt bound to avow 
publicly the change of view brought about by his later in- 
vestigations. But Darwin's views had not yet been concen- 
trated and expressed as a whole. A summary of them was 
given to the world in the ' Origin.' The sledge-hammer effect 
of this was still to be experienced. 
^ The present Professor of Botany at Glasgow. 
