88 ORGANS AND FUNCTIONS OF PLANTS. 



in plants different from those supposed to have been 

 introduced from the soil, it is not to be inferred that 

 the plants have created these, but that they have 

 gradually taken them up in very minute portions till a 

 considerable quantity has been produced. 



It is proper to confess, however, that we are still 

 much in the dark upon this interesting subject, it 

 being extremely difficult, if not impossible, to trace 

 the fluid taken up by a plant after it passes beyond 

 the surface. 



The Spongelets or Suckers. 



We have elsewhere seen that many insects support 

 themselves wholly by suction l ; and we now remark 

 that all plants do the same. For this purpose, they 

 are furnished, not with a single sucker like the leech 

 or the flea, but with many. De Candolle describes these 

 suckers, which he terms spongelets 2 , as resembling a 

 minute sponge, full of pores, inferred, when they can- 

 not be detected, from the fact of fluids actually passing 

 into them. The spongelets are always placed on the 

 extreme tips of the rootlets or smallest fibres of the 

 root, and are composed of an expanded tissue of small 

 roundish cells, often as soft as pulp. 



It is important to remark, that the spongelets will 

 not admit any fluid much thicker than water, and 

 accordingly when plants are watered with the drainings 

 of the farmyard in an undiluted state, the pores of the 



(l) See ALPHABET OF INSECTS, p. ( 

 (2) In Latin, Spongiolum* 



