leaf will be dissolved. After a few minutes we wash the sec- 

 tions in water on a glass 

 slip, and stain them with a 

 solution of eosin. If the 

 sections were carefully 

 made, and thin, the threads 

 of the mycelium will be 

 seen coursing between the 

 cells of the leaf as slender 

 threads. Here and there 

 will be seen short branches 

 of these threads which 

 penetrate the cell wall of 

 the host and project into 

 the interior of the cell in 

 the form of an irregular 

 knob. Such a branch is a 

 haustorium. By means of 

 this haustorium, which is 

 here only a short branch 

 of the mycelium, nutritive 

 substances are taken by the 

 fungus from the proto- 

 plasm or cell-sap of the 

 carnation. From here it 

 passes to the threads of the mycelium. These in turn supply 

 food material for the development of the dark brown gonidia, 

 which we see form the dark-looking powder on the spots. 

 Many other fungi form haustoria, which take up nutrient 

 matters in the way described for the carnation rust. 



160. Nutrition of the dodder. — The dodder (cuscuta) is an 

 example of one of the higher plants that is parasitic. The stem 

 twines around the stems of other plants, sending short conical 

 processes termed haustoria in their tissues. By means of these 

 the nutriment is absorbed from the host. The means of absorb- 



Fig. 63. 



Carnation rust on leaf and flower stem. 



From photograph. 



