108 PROF. BOWER : 
of their construction. The System of Linnæus was the culmination of such 
efforts. But later the method became more “natural,” being based, like 
that of De Jussieu, upon a wider area of diagnostic features. This change 
led up to the period, about the opening of the 19th Century, when Sir William 
Hooker began his life's work. He joined with vigour in the recognition, 
delineation, and description of new forms, and the classification of them in 
their natural affinities. Under his hands the Glasgow Garden became one 
of the most notable in Europe. The port of Glasgow traded with every 
quarter of the globe. This gave unusual facilities, and Sir William used 
them to the full. The result was that amazing output of descriptive work 
which marked his tenure of the Glasgow Chair, and it was continued at Kew 
till the end of his life in 1865. 
The five volumes of the ‘Species Filicum, condensed and erystallized 
later into the ‘Synopsis Filicum,’ constituted his magnum opus. It may 
be taken as a typical example of the best systematic works of the immediate | 
Pre-Darwinian Period. It gives an insight into the method of its author, 
and in some degree reflects his outlook. The work is analytie rather than 
synthetie, though flashes of synthetic inspiration are scattered through its 
pages. It describes, from personal observation and in meticulous detail, 
a vast number of forms. The specific diagnoses and records of distribution 
are a veritable mine of exact statement, which later systematists have freely 
worked. But the author did not originate any new system. He adopted and 
modified that of Presl's* Tentamen.' The chief merit of the book will always 
rest upon what its very title conveys—that it gives a conspectus of all the 
then known species of Ferns. The limits of the genera in which those species 
were grouped gave rise to differences of opinion with other writers. Presl 
had published his ‘Tentamen’ in 1836, somewhat earlier than Sir William 
Hooker's beautifully illustrated work on the ‘Genera Filicum. Comparison 
of the two books shows that there is a wide discrepancy in the number 
of their genera. Where Presl recognized 132 genera, Hooker retained 
only 75. This at once indicates a salient feature of his method. He 
merged many genera, ranking them as sub-genera under more comprehensive 
headings. One reason for this was his mistrust of anatomical data, of which 
Presl made great use. But at least one other reason influenced him,—that 
of convenience in diagnosis. An example will illustrate this point. In 
placing Plagiogyria under Lomaria he objects to the use of its oblique 
annulus as a diagnostic character, because of its requiring microscopic 
examination, and the inconvenience “in a work whose main object is to 
assist the tyro in the verification of genera and species.” Natural habit, 
he remarks, is often a safer guide than minute microscopic characters. 
And further, he states that “those Botanists who have showed themselves 
peculiarly addicted to multiplying genera have not always taken Nature as 
their guide, nor succeeded in eliciting a simple and tangible arrangement,” 
