18 STRUCTURE AND PROPERTIES 



imbibe moisture, and seem to act like small and 

 very absorbent sponges. The radical spongioles 

 are situated on the fibrous extremities of the roots, 

 and it is by these extremities only that the absorp- 

 tion of juices by the roots takes place.* Senebier 

 placed two roots in such a manner that in the one 

 the extremity alone touched the water, while 

 the whole surface of the other root was covered 

 by it, except the point, which was out of the 

 fluid : the former took up water in the ordinary 

 manner, the other imbibed no sensible quantity. 

 The root fibre and its spongiole may be well 

 observed in the common duckweed, in which it 

 hangs from the under surface of every leaf. 

 Spongioles are found on the stigmas and on the 

 seeds of plants. 



9. The name of Lenticular glands has been 

 given to a peculiar kind of spots observed on the 



* Dr. Carpenter, in his Vegetable Physiology ( 106), 

 mentions a strong instance of the practical value of an 

 acquaintance with the nature and structure of the spon- 

 aioles, in the removal of some vines from Shropshire into 

 Norfolk, which was effected without the smallest injury 

 to the plants by first digging a trench round them at such 

 a distance as included all their roots, and then removing 

 the earth " not with spades and trowels, but with the 

 fingers; every fibril being thus uncovered without in- 

 jury." The vines bore an abundant crop in the following 

 season. 



