54 MYCOLOGY 



down of Lhe whole fruit body has been proved to be a process of auto- 

 dig^estion. When the hyphae are colored, the color is confined generally 

 to the cell wall, although Biffen states that in some hyphae the color 

 is located in the contents, the wall remaining colorless. Spores are 

 colored frequently as in Ascobolus which grows on manure. The spores 

 at first colorless change through pale lilac to clear deep amethyst. The 

 coloring matter is confined to the spore walls, but in some cases the 

 contents are colored, while the wall is colorless, as in many a^ciospores. 



Physiology or Fungi 



The research of recent years in the nutrition of fungi has shown 

 that nine chemic elements are necessary for the structure and complete 

 development of the true fungi. These elements are carbon, hydrogen, 

 oxygen, nitrogen, sulphur, phosphorus, potassium (or rubidium), 

 magnesium and iron. Analysis of the ash. constituents of fungi shows 

 that phosphoric acid and potassium are the chief ones, the latter form- 

 ing seldom less than one-quarter and sometimes one-half of the total. 

 Phosphorus is present in the ash to the extent of 15 to 60 per cent, 

 and is eagerly absorbed by growing fungi, as is shown by Dcedalea 

 quercina, which in its growth completely extracted the phosphoric 

 acid from decayed wood. Winogradsky, Meyer, H. Molisch and W. 

 Benecke have shown that magnesium is indispensable to fungi. Be- 

 necke has demonstrated a considerable difference in development shown 

 by two, otherwise equal, specimens, the one grown without magnesium 

 and the other in a medium containing 0.0025 mg- of crystallized magnes- 

 ium sulphate per 25 c.c. and Guenther has proved that 0.005 "^g- of 

 magnesium sulphate was necessary to induce a sowing of Rhizopus 

 nigricans to grow at all. 



As to iron, as an indispensable element before the matter was put 

 to the test, it was thought that fungi being chlorophylless did not 

 require iron like the green plants in which iron was concerned in the 

 formation of chlorophyll. The experiments of Hans Molisch tend to 

 prove the essential importance of iron in the nutrition of the true fungi 

 for in presumably iron-free cultures, the spores of Aspergillus niger 

 did not develop beyond the formation of a sickly mycelium. Similar 

 results were obtained with sowings of pressed yeast cells, spores of 

 Mucor racemosus and a species of Penicillum. Iron in addition to 



