Sense-Life and Sensibility 



intelligence. Striking as are many of the purposeful 

 adaptations to be found in plant life, such an assumption 

 cannot possibly be maintained. 



But it is necessary to abandon speculation and try 

 to show how much of more recent work tends to ex- 

 plain this difficult question of the purposeful working 

 of plant protoplasm. 



There is first the extraordinary sensitiveness of both 

 leaves, stems, and petioles to sunlight. According to 

 Darwin, grass seedling will curve towards a source of 

 light so faint that it is indistinguishable to a human eye. 

 The careful experiments of Haberlandt have shown that 

 not only the leaf blade but even its stalk are so affected 

 by sunlight that both move and so arrange or display 

 the green surface to the best advantage. One plant, 

 Fittonia, has a tiny cell the shape of a biconvex lens 

 placed at the top of prominent epidermis cells. 5 



That this acts like a lens scarcely admits of any 

 doubt, and it will focus the light upon some particular 

 layer inside the leaf. Should this focus be a sensitive 

 protoplasm-surface which will react to light, then "one 

 can see that the leaf may, by the reactions of this pro- 

 toplasm, shift its position until it is at the most desirable 

 angle for illumination. 



These peculiar, lens-like cells have been compared to 

 the primitive simple eyes found amongst many of the 

 lower animals. 



That they do act like lenses scarcely admits of any 

 doubt, for Haberlandt and others have made photo- 

 graphs by means of these epidermis cells. Mr. Harold 

 Wager exhibited at the Linnean Society, i9th Nov. 1908, 

 several excellent photographs of flowers, landscapes, 

 houses, and even of figures taken by means of these 

 epidermis cells. Even autochrome plates (Lumiere's) 

 were used by him. 6 When, as in some of Haberlandt's 



145 K 



