98 



Elementary Plant Physiology. 



plants with such tubercles 

 can fix and make use of 

 the free nitrogen of the air. 

 102. Nutrition of 

 a saprophyte. — No in- 

 dependent saprophytes, or 

 species which live on dead 

 organic matter, are known 

 among the seed plants. 

 The fungi comprise a 

 large number of species 

 which obtain their nutri- 

 ment in this manner. 

 Their method of growth 

 and absorption of food 

 may be observed as fol- 



Fig. 71. — Seedling of hemlock {Tsaga Cana- 

 densis) with mycorrhizal roots. After Lloyd. 



lows : place under a bell jar for 

 two days a fragment of bread 

 which has been moistened with 

 water. A number of slender 

 hyphse of a mold may be seen 

 arising from the bread. Tear 

 apart a bit of the bread, and ex- 

 amine with a magnification of 

 about 60 diameters. The ab- 

 sorbent branches of the mycelia ^. , . . . , 



Fig. 72. — Longitudinal section of 



may be seen ramifying through root of hemlock (^Tsuga Cana- 

 the bread. These submerged *"™5- The outer, shaded layer is 



inhabited by a fungus. After Har- 



hyphffi take up sugars and other jow. 



