208 PROCEEDINGS OP THE 



secretions. The plants known as decidedly insectivorous are 

 evidently closely related in respect of nutrition to this class, and 

 so far as such plants are concerned, they are either rootless or are 

 never found to possess large or highly-developed roots, and never 

 grow in rich soils in which plentiful absorbable organic matter 

 exists. Examples are afforded by our Drosera, Pinguicula, and 

 Utricularia, and by the exotics Dionaea mus^nda and Aldrovanda, 

 all of which are either aquatic, or grow in swamps and marshes; 

 by Drosophyllum lusitanicum, which is found on dry barren hill- 

 sides in Portugal and Morocco. It would thus seem that the 

 adaptations for capturing insects are only or mainly developed in 

 plants that have little chance of obtaining nitrogenous nutriment 

 from the soils in which they grow. Probably most of the higher 

 plants can live and flourish without absorbing any organic matter; 

 but, however that may be, it is an undoubted fact that a very 

 large proportion of them do usually derive a part of their nourish- 

 ment from this source. This is markedly the case in many 

 cultivated plants, which absorb organic manures largely, and are 

 thereby stimulated to increased growth and development, and to 

 greater activity in assimilating. In this latter respect these 

 cultivated plants differ widely from typical saprophytes and 

 parasites, which have come to depend wholly on supplies of 

 organic matter, and have given up assimilating for themselves. 



If we regard exclusively the amount of nutrition derived by 

 vegetable parasites from foster plants, those which are, after 

 attachment, wholly dependent on their hosts will be held to be 

 completely parasitic, as Lathraea, Cuscuta, Orobanche; while those 

 which supplement their drafts on their hosts by assimilating for 

 themselves will only rank as sub-parasitic, as Viscum. If we 

 regard, however, the mode of attachment to the foster plant, the 

 class of complete parasites will include Viscum, which in one 

 respect — that of germinating on its host — is more distinctively 

 parasitic than any other British species, all the others germinating 

 in the soil and subsequently attaching themselves. There is a 

 group of plants, including Euphrasia, Mela/nvpyrwm, and the like, 

 which, like Lathraea, turn black when dried, and are usually 

 regarded as partial parasites. These plants, however, not only 

 assimilate for themselves, but their attachment to other plants is, 

 at the most, a very superficial one. The glandular pubescence of 

 many of them would, besides, seem to indicate the atmosphere as 



