174 FRANCIS DARWIN. 



which seems at all capable of connecting the observations 

 made on the properties and behaviour of these filaments 

 is the following. That the glands on the teasel were 

 aboriginally (i.e. in the ancestors of the Dipsacacese) mere 

 resin-excreting organs. That the protoplasm which comes 

 forth was originally a necessary concomitant of the secreted 

 matters, but that from coming in contact with nitrogenous 

 fluids it became gradually adapted to retain its vitality and 

 to take on itself an abortive function. And that this 

 power — originally developed in relation to the ammonia in 

 rain and dew — was further developed in relation to the 

 decaying fluid accumulating within the connate leaves of the 

 plant. 



