204 Dynamic Theory. 



numerous white filaments, each of which bears a sporangium on top. 

 The spores can be sown and produce mycelium in a solution of sugar 

 or other nourishing fluid if excluded from the air. 



The sixth family is called the Ascomycetes. In these the sporangia 

 are themselves contained for a longer or shorter time in larger sacs 

 called asci. In some the asci soon disappear, leaving the sporangia 

 free ; in others they persist till the spores are mature, when they 

 burst and liberate them. Some are found chiefly on animal sub- 

 stances. Others occur on living plants. The order called Perisporiacei 

 contains many destructive genera, as the Hop Mildew, Pea Mildew, 

 Hose Mildew, &c. They cover the surface of leaves &c. , with a thick, 

 white coating. 



In some of these organisms several different kinds of fruit are pro. 

 duced from the same n^celium, sometimes as man} 7 as five or six. 

 They call to mind the alternate generation of some low animal forms. 

 There is an order of underground bulbous fungi belonging to this 

 family. They are called the Tuberacei, the most important genus being 

 the edible delicacy called the truffle. 



Many of the fungi are self luminous, probably from phosphorus con- 

 tained in their tissues. One example cited by Cooke was reported by a 

 traveler in Australia. A large specimen of an Agaric, sixteen inches in 

 diameter, was found and hung up in a sitting room, where it gave light 

 for four or five nights till it dried up. All parts of the Agaric, ex- 

 cept the top of the cap, give this light of a pale greenish tint. Cer- 

 tain species, the Boletus luridus and others, on being cut or bruised 

 exhibit an intense and, in some cases, a vivid blue. This color is taken 

 on very quickly, almost instantaneously. This is attributed to a rapid 

 change in the molecular constitution of the plant on exposure of the 

 tissues to the air. Many of the fungi contain a milky juice, and when 

 the flesh is cut or bruised and this juice exposed to the air its color 

 turns to a dull livid green. 



Fungi are generally strongly odorous, and disagreeably so. Most of 

 the fleshy forms smell of nitrogen while decaying. li -Peziza Venosce" 

 when fresh has a strong odor like aqua f ortis ( nitric acid ). The 

 growth and decay of fungi are both extremely rapid. A puff-ball or a 

 toad-stool will grow enormously in a night, and in the same length of 

 time a mass of paste may be covered with mould. < ' In a few hours a 

 gelatinous mass of reticularia will pass into a bladder of dust, or a 

 coprinus will be dripping into decay." These facts point clearly to the 

 delicacy of the molecular constitution of these fungi, and the extreme 

 fickleness of their constituents. Nitrogen, which appears to be largely 

 concerned, forms always exceedingly unstable compounds. 



The spores of fungi are disseminated through the air like dust, and 



