234 



BOTANY OF THE LIVING PLANT 



second method has been termed Asymbiotic germination, and is the 

 more successful. 



It seems probable that in the association called endotrophic mycor- 

 rhiza the initiative comes from the fungus, by an essentially parasitic 



Fig. 162. 

 Germination of the orchid Odontoglossum. All sections are median longitudinal. 

 (1) a seed ; (2) shows the extent of development after three months under ger- 

 minating conditions in the absence of the fungus ; (3) shows the development 

 obtained in a similar period in the presence of the fungus. From this tuberous 

 structure the root and shoot later arise. Note the heavy infection and signs of 

 digestion. p= absorbing hairs (through which infection occurs). s = stoma. ( x 100.) 

 (From Bernard, Ann. Sci. Nat.) 



attack from the soil into the tissues of the host plant. By digestion 

 the intrusive fungus may be kept under control, while incidentally 

 the higher plant gains materials which may be of value for its own 

 nutrition. The same view can be taken of ectotrophic mycorrhiza, 



