CELLULAR ANATOMY OF THE ROOT 22/ 



minutes in strong potash, then remove and 

 wash it and mount it on a slide in water.) 

 50. From observation of the appearance of the young 

 roots with their remarkable development of hairs, 

 it would seem probable that these form the struc- 

 ture for absorbing liquids into the plant, and 

 experiments have proven that this is the case. 

 Since, however, observation proves that the hairs 

 and the root tips have no openings, but form a 

 closed system, it is plain that the water must be 

 absorbed through imperforate membranes. The 

 question then arises, Is there any physical pro- 

 cess by which liquids can be absorbed through 

 imperforate membranes ? This may be answered 

 from Experiment 9, where a membrane (a sort 

 of gigantic hair) has water outside and a solu- 

 tion of sugar inside, precisely as the root hair 

 has. In this experiment, the membrane and an 

 absorbing plant stand side by side. 



Can liquids be absorbed through imperforate mem- 

 branes ? 



Answer from Experiment 9. 



It is also important to know whether the absorp- 

 tion is merely a passive rilling of open tubes or 

 an active process that can overcome resistance. 

 This may be learned by attaching a pressure 

 gauge in place of an open tube, as has been 

 done in Experiment 10. 



