quite peeled off at the spongiole and become destroyed, while 

 further upwards it still adheres firmly ; a similar case also came 

 under M. Ohlert's observation. The calyptrae upon the 

 spongioles of the thick aerial roots of the Pandani, to which 

 DeCandolle first drew attention,, are frequently to be seen in 

 the Botanic Garden of Berlin ; they are for the most part 

 thick membranes, consisting of several layers of cells, which 

 are here torn off from the hinder part of the root by the rapid 

 growth of the spongiole ; after some time this decortication is 

 repeated in the part of the root which has grown subsequently. 

 M. Ohlert's experiments respecting the elongation of the 

 fibrils have completely confirmed Du HamePs discovery that 

 this elongation takes place only at the extremities. 



He has endeavoured to prove by observations, that the cur- 

 rent opinion, that the roots absorb exclusively by the spon- 

 gioles and not with the lateral surfaces, is erroneous, or at 

 least, that the reasons brought forward to prove this are not 

 sufficient. Young plants of Pisum sativum, Lupinus luteus and 

 Calendula offidnalis were so placed with their roots in water 

 that only the radicles were immersed about three lines deep 

 in it. Even after a few hours the roots were withered, and 

 after a few days quite dry ; only that part of the root which 

 was inserted in the water retained its turgescence. Upon this 

 a quantity of plants were so placed in water, that the extre- 

 mities of the fibrils projected out of the water, while the en- 

 tire lateral surfaces were immersed. Also when the apex was 

 coated with gum-lac varnish, the plants continued to grow 

 extremely well if the entire surfaces of the fibrils were under 

 water. From these experiments he concludes, that the fibrils 

 do not absorb the moisture by the spongioles, but at the sides, 

 or over the entire surface. I can however hardly agree with 

 this conclusion ; for I can also bring forward experiments 

 which prove that the apex is, and indeed very actively, engaged 

 in the process of absorption ; this subject, as also my observa- 

 tions on the structure of the spongioles, are accurately detailed 

 in the second part of my Vegetable Physiology, in which are 

 refuted the received opinions respecting the so-called spon- 

 gioles of the root, which do not exist in nature. It must cer- 

 tainly be admitted that plants absorb with the whole surface 

 of their roots ; this surface however is in many cases, and espe- 



