OTHEE METHODS OF OBTAINING FOOD 205 



developed in rows at the points of contact. Haustoria 

 spring from these suckers and penetrate the host, extending 

 inwards till they reach the wood (fig. 102). The part below 

 the attachment dies shortly after this relationship has been 

 established, and the parasite is left attached to the host. 

 In its further growth it continues to twine around the latter, 

 putting out numerous branches, which also form similar 

 coils, so that the host is completely immeshed in the 

 twining stems of the parasite. The latter bears no leaves 

 and possesses no chlorophyll in any part, so that it derives 

 all its food in fully elaborated form from the tissues of the 

 host. Cuscuta produces numbers of flowers on its branches, 

 and from them are developed fruits and seeds. The para- 

 sitism is complete, and the relation frequently leads to the 

 death of the host which has been 

 attacked. 



Parasitic plants are very fre- 

 quently met with among the fungi 

 and the Bacteria. The former pene- 

 trate the living cells of the plant they 

 infest, or in a few cases ramify 

 between them, sending haustoria into 

 the interior of the cells between which 

 the mycelium grows (fig. 103). They 

 make use of the contents of the cells, 

 destroying and absorbing the living 

 substance as well as any formed 

 materials, which may be present. In 

 many cases also they destroy the 

 cell-walls, and utilise the carbo- 

 hydrate materials of which the latter 



consist. Their ravages only cease with the death of the 

 organism. 



The power of living plants to assimilate the food 

 manufactured by others is taken advantage of in the 

 processes of grafting and budding. In these operations a 

 slip of a particular plant is inserted into a wound made 



FIG. 103. CELLS OP POTATO 

 PLANT INFESTED WITH 

 Phytophthora. 



by hyplia running between 

 the cells and sending 

 haustoria (a) into their 

 interior. 



