l25 ^HE Kant WorlI). 



7. The generic coefficient. 



8. Relative relation of the great groups of the plant king- 

 dom. 



9. Resume. 



According to the author an association is to be considered 

 as an organic unit; its constituents exhibit a definite correlation, 

 and their relative occurrence as regards number and kind pre- 

 sents a constancy which is in striking contrast with the variation 

 in external conditions to which they are exposed. The distribu- 

 tion of species in a given plant formation results from the com- 

 bined operation of three groups of factors: 1. Ecological fact- 

 ors (cli iiate and soil) ; 2. Biological factors (means of adaptation) ; 

 3. Sociological factors (competition and accommodation.). 



Pitard and Proust have recently published an extended ac- 

 count, in a work of upward of 500 pages, of the flora of the 

 Canary Isles (Paul Klincksiek, Paris), from which it appears that 

 the flora of theCanaries includes 1,352 indigenous or spontaneous 

 species. Of these 350 are reckoned as ubiquitous, 534 as be- 

 longing to the Mediterranean region, and 468 as endemic or 

 Atlantic. The ubiquitous species are chiefly temperate, though 

 a relatively small number are tropical. The endemic elements 

 are connected especially with Mediterranean species, others 

 have African affinities, and some rare Atlantic types have their 

 nearest relatives in America or eastern Asia. The endemic 

 forms, including varieties, species and genera, represent three 

 successive degrees of intensitv, with which the climate and in- 

 solation have acted on Mediterranean types resulting in their 

 modification. The proportion of endemic genera is equalled or 

 exceeded only by St. Helena, Juan Fernandez, the Sandwich 

 Islands and New Zealand. 



Hayek, in treating of the xerotherm plant relicts in the 

 eastern Alps, describes the occurrence of numerous colonies of 

 thermophilous plants which belong to an earlier period in 

 which a warmth-loving flora had settled in this region. The 

 colonies located in the heart of the Alps, formerly covered with 



