fact that these organs develop only on young immature 

 leaves where groups of peculiar, perishable gland-hairs are 

 found; beneath these dead mucous glands the substitute 

 secretive organs originate in the inner tissue. It is of no 

 importance to state in what particular cells they originate. 



Suffice it to say that they are colorless capillary tubes 

 originating in various cells; projecting like the hairs of a 

 brush, containing living protoplasm and evanescent chlor- 

 ophyl. It is also important to note that this new organ 

 is immediately connected with the water-conducting system 

 consisting of bundles of vascular fibres. Haberlandt 

 furthermore indicates especially that these organs when 

 viewed in connection with the process of secretion give 

 evidence of an active vital principle as well as of simple 

 mechanical filtration. 



These substitute organs are all indeed well adapted to 

 their purpose and adequately replace the old secretive 

 organs, but they so easily dry out and are so little pro- 

 tected that after a week they become parched and die be- 

 cause wound-cork forms under them. The leaf no longer 

 produces new hydathodes, but on its lower side it pro- 

 duces growths that function as vesicles, by means of which 

 it continues to sustain itself. 



Haberlandt furthermore records a phenomenon per- 

 haps analogous to this on the grape-vine, but with this 

 exception the case described by him is unique. In order 

 to pass any further judgment regarding it, we should have 

 to ascertain whether the whole phenomenon is not a case 



57 



