THE SPONGIOLES AND SUCKERS. 81 



whilst the other has its whole surface plunged in, 

 excejit its extremity, which is raised in the air, the for- 

 mer will suck up just as usual, and the other will not 

 absorb any perceptible quantity. This experiment, 

 which can easily be repeated with a Carrot, or Scorsonera, 

 evidently proves that the extremity of roots is endowed 

 with an entirely peculiar hygroscopic power ; but if we 

 reflect that the roots, as we shall show by and by, increase 

 only by their extremities, we shall be strongly led to 

 believe that that which essentially distinguishes this 

 extremity, is, that it always presents a young membra- 

 nous surface, which is not obliterated by age, and which 

 enjoys in all its plenitude the hygroscopic property of 

 vegetable tissue : we should consider, therefore, how the 

 extremities of roots present phenomena so distinct, 

 without their anatomical structure offering any thing 

 remarkable. 



Carradori, who has repeated the experiments of Sene- 

 bier, obtained the same results when he employed the 

 roots of the Radish, or the highly developed ones of 

 other plants. He varied the experiment by placing a 

 Radish, first, with its roots in the water and its spon- 

 gioles out of it ; in this case its leaves withered : after- 

 wards the 'spongioles were put into the water, and the 

 body of the root into the air, and then the leaves 

 regained their freshness. When, on the contrary, he 

 submitted to the same tests young plants of Corn, or the 

 Lupine, still bearing their cotyledons, he saw that even 

 when the roots had their extremities out of the water, 

 they continued to vegetate : he has concluded from these 

 facts, that the roots absorb the water by their whole 

 surface ; but from his own accounts, I conclude only that 

 these young plants are nourished for some days at the 

 expense of their cotyledons. 



The largest Radical Spongioles which I have met 



VOL, I. G 



