76 PARASITIC PHANEROGAMS OF QUEENSLAND, ETC. 



these reagents ; that of the parasite attains a golden yellow 

 colouration by them. Ammon. molybdate in nitric acid gives a 

 dark brown precipitate with infusions of the ironbark, and a 

 blood-red colouration with those of the parasite. Copper acetate 

 gives a dark brown precipitate with ironbark ; whereas infusions 

 of Loranthus get greenish-yellow by it. 



These reactions show plainly that the parasitic plants 

 maintain vigorously their own life economy and that they do not 

 only use the ready formed sap of the host for the construction of 

 their body. 



The other species of Loranthus and those of Viscum give 

 similar reactions. 



The species of the Dodder (like Cuscuta australis, R. Br.) 

 also differ chemically very much from the leguminous plants on 

 which they generally grow. These parasites are (nearly) destitute 

 of chlorophyll. Their tissue consists for the most part of a juicy 

 parenchyma with only a few scalariform vessels. There is plenty 

 of starch in the cells which must be derived from the host, as 

 the starch can only be produced by chlorophyll. 



Infusions of the parasite are stained green with ferric salts 

 and they contain more tannic acid than those of the Lucerne 

 {Medicayo sativa), on which the dodder grows. Besides this, 

 there is a yellow colouring matter present which is turned golden 

 by caustic potash and by sulphuric acid, and which is bleached 

 by nitric and hydrochloric acid. No such dye is contained in 

 infusions of the host of the parasite. 



The species of the Climbing Laurel {Cassytha) are very 

 common parasites in the Australian bush. They grow mostly 

 on young eucalypts and destroy them by taking the light away. 

 Lafusions from Cassytha melantha gave the following colour 

 reactions : — Ferric acetate, green ; caustic potash, golden yellow ; 

 ferro-cyanide of potassium in ammonia, brown ; copper acetate, 

 yellow. These reactions are altogether different from those of 

 the common trees on which the parasite lives. 



Both genera, Cuscuta and Cassytha, are fastened to the 

 plants by means of so-called haustoria. These I found to con- 

 sist of flattened parts of the surface of the parasite on the concave 

 side of the coils, emitting a kind of roots which penetrate into 

 the bark or into the epidermis and into the inner tissues of the 

 host. 



