EcroTRuriiic mycorhiza. 



95 



Fig. 17.— Spruce seedling in third year, gi-own in clay-loam. Typical ciil liku 

 mycorhiza are absent. The strong root to the right shows, on its newer jiarts 

 and on all lateral roots, only root-hairs and no fungus. The remaining roots are 

 not modified in any way — some ai-e covered with loose fungal caps, others 

 have both fungal caps and root-hairs, while others are quite free from fungi, 

 (v. Tubenf phot.) 



