Chapter II — 15 — History 



islands of the Antarctic at one time formed part of a single flora, oc- 

 cupjang a continent larger than that now found in the Antarctic 

 Ocean. 



Part III of this same work, devoted to the flora of Australia and 

 Tasmania, appeared in i860, after the pubHcation of Darwin's "Ori- 

 gin of Species", which had a great influence on Hooker but did not 

 advance any views seriously contradictory to his own. In this Part 

 III we find two sections of particular interest: 3. "On the general 

 phenomena of distribution in area" and 4. "On the general phenomena 

 of the distribution of plants in time". In the former the author draws 

 the conclusion that many phenomena in the present distribution of 

 plants cannot be explained by existing factors and that to understand 

 them it is necessary to study past changes in climate and in the distri- 

 bution of dry land. In Section 4 Hooker examines the paleobotanical 

 data available at the time of the publication of his work and comes to 

 the conclusion that the problem of the distribution of plants is ex- 

 ceedingly complex. He advances the proposition that changes in the 

 surface of our planet — lands being replaced by seas and valleys by 

 mountain chains — take place in a relatively short interval of time, as 

 compared to the age-long existence of some genera and even species of 

 plants. 



In 1855 Hooker began pubHcation of his "Flora Indica". In the 

 first and only volume of this "Flora" (it was later replaced by his "Flora 

 of British India") there is an "Introductory Essay" of exceptional im- 

 portance for an understanding of the history of development not only 

 of the flora of India but also of modern tropical flora in general. In 

 1862 there appeared another important work, "Outlines of the distri- 

 bution of arctic plants", giving an analysis of arctic flora and data 

 for the establishment of its origin. Of great interest also is Hooker's 

 "Lecture on Insular Floras" — delivered in 1866 before the British 

 Association for the Advancement of Science — in which he again returns 

 to the problem of the origin of insular floras, their interrelations, and 

 their relations to continental floras. 



Reviewing Hooker's work, we see that he put a number of entirely 

 new problems, concerned not so much with regularities in the distribu- 

 tion of separate species as with the question of the origin of whole 

 floras, determined on the basis of an analysis of the areas of distribu- 

 tion of the component species. This new direction of investigation 

 proved in the highest degree fruitful and constituted a great impetus 

 to work in this field. 



From the foregoing it is evident that by the middle of the nine- 

 teenth century the question as to the geographical distribution of 

 organisms was for many investigators, such as Lyell, Forbes, Hooker, 

 and others, in its basic features entirely clear. Nevertheless, the doc- 

 trine as to the immutability of species and their existence as a result 

 of separate acts of creation was still firmly rooted, due chiefly to its 

 connection with religious views, and shackled the minds even of out- 

 standing thinkers. 



In 1859 there appeared Darwin's "Origin of Species". The revo- 

 lution which this book produced not only in biology but in all man's 

 thinking naturally affected the development of our branch of science 



