THE FUNGI 151 



undivided hyphae of some of the Phycomycetes, active streaming of 

 the cytoplasm can sometimes be demonstrated. Where the hyphae 

 are colored, this may result from a coloration of the cell-wall, as in 

 Mucor, or from the presence of pigment-granules within the cyto- 

 plasm, e.rj. the scarlet pigment of species of Peziza. 



Mycelium. The mycelium may live but a few days, or it may 

 grow indefinitely, as in the case of many species of Toadstools, where 

 the mycelium, buried in the ground, continues to spread, giving rise 

 to successive crops of the fruiting bodies. 



The hyphae of the fruiting structures are usually more compact, 

 and often grow together, so that a section has the appearance of a 

 true parenchymatous tissue. 



Reproduction. The lower Fungi, or Phycomycetes, resemble cer- 

 tain Algae in their reproduction. They may form free-swimming 

 zoospores, or sexually produced resting-spores closely resembling 

 those of the Green Algae. The more typical Fungi, however, differ 

 much in their reproduction from any green plants, and it is very 

 hard to make any comparisons between them. A great variety of 

 non-sexual spores are produced, which generally differ much from 

 those of any other plants. The most important of these will be 

 considered in connection with the special groups to which they 

 belong. 



Sexual Reproduction. Sexual reproduction is known for only a 

 small part of the Fungi, and has been apparently quite lost in a very 

 large part of the group. In some of the Phycomycetes, fertilization 

 is effected much as in the Green Algae, but in the more specialized 

 Fungi the reproductive organs are more like those of the Eed Algae, 

 and as in those, there is not a resting-spore produced, but a com- 

 plicated spore-fruit, or sporocarp, from which the spores are produced 

 secondarily. With very few exceptions, fertilization is effected by 

 direct conjugation of the antheridium with the carpogonium, or by 

 means of non-motile sperrnatia like those of the Rhodophyceae. 



Affinities of Fungi 



A small number of the Fungi, the Phycomycetes, or Alga-Fungi, 

 show a more or less evident resemblance to some of the Chlorophy- 

 ceae, and perhaps have some such relation to them as do such color- 

 less parasites or saprophytes as the Dodder, or Indian-pipe, to their 

 green relations among the Flowering Plants. The occurrence of such 

 parasitic Algae as Phyllosiphon, or Mycoidea, make the derivation from 

 Algae of quite colorless forms, or Fungi, by no means improbable. 



The greater number of Fungi, the Eumycetes, show much less 

 evidence of being derived directly from algal ancestors, and their 

 affinities are in most cases very obscure. 



