DEPENDENCE OF PLANT FOKM ON SOIL AND CLIMATE. 495 



but the whole of the protoplasm of any species possesses the specific constitufcion of 

 that species. 



It is of the greatest importance not only for the existence of the species, but 

 also for the origin of new species, that the protoplasm, by reason of its specific 

 constitution, should always take the same form. New species can only arise from 

 those already in existence. This is equivalent to saying that the protoplasm of 

 an existing species must undergo alterations in its constitution. Living protoplasm 

 with new specific constitution must be produced from what already exists. How 

 such a fundamental alteration is effected can only be guessed at by roundabout 

 methods. One has to be content, as in so many other instances, with the results 

 of experiment and experience, and with ascertaining, above everything, what in- 

 fluences are capable of altering the outward form of a whole or part of a plant 

 either temporarily or permanently. 



2.— ALTEEATION IN THE FOEM OF SPECIES. 



Dependence of Plant Torm on Soil and Climate. — Influence of Mutilation on the Form of Plants. — 

 Alteration of Form by Parasitic Fungi. — ^Alteration of Form under the Influence of Gall- 

 producing Insects. — Origin of New Forms by Crossing. 



DEPENDENCE OF PLANT FOEM ON SOIL AND CLIMATE. 



The little town of Kitzbiihel, in the North-east Tyrol, has a very remarkable 

 position. On the north rises the Wilde or Vordere Kaiser, a limestone chain of 

 mountains with steep, pale, furrowed sides, and on the south the Rettenstein group, 

 a chain of dark slate mountains whose slopes are clothed far up with a green 

 covering. The contrast presented by the landscape in its main features is also to 

 be seen in the vegetation of these two mountain chains. On the limestone may be 

 seen patches of turf composed of low stiff Sedges, Saxifrages whose formal rosettes 

 and cushions overgrow the ledges and steps of the rugged limestone, the yellow- 

 flowered Auricula, the Rock-rose-flowered Rhododendron, and white-flowered Cinque- 

 foil adorning the gullies, dark groups of Mountain Pines bordered with bushes of 

 Alpine Rose; and opposed to these, on the slate mountains, are carpets of thick turf 

 composed of the Mat-grass sprinkled with Bell-flowers, Arnica Tuontana and other 

 Composites, groups, of Alpine Alder and bushes of the rust-coloured Alpine Rose — 

 these are contrasts in the plant-covering which would strike even a cursory observer, 

 and would lead a naturalist to ask what could have been the cause. No wonder that 

 the enthusiastic Botanist, Franz Unger, was fascinated by this remarkable pheno- 

 menon in the vegetable world. In his thirtieth year, furnished with a comprehensive 

 scientific training, he came as a doctor to Kitzbiihel, and with youthful ardour 

 he used every hour of leisure from his professional duties in .the investigation 



