Two great divisions are recognized in the Fungi: (i.) the Pycomycetes or Algal Fungi, which retain a definitely sexual method of reproduction as well as asexual (vegetative) methods, and (ii.) the Mycomycetes, characterized by extremely reduced or very doubtful sexual reproduction.
The fungus seems, on the other hand, to stimulate the algal cells to special development, for those in the lichen are larger than those in the free state, but this is not necessarily adverse to the idea of parasitism, for it is well known that an increase in the size of the cells of the host is often the result of the attacks of parasitic fungi.
(13) Phycomycetes (Algal fungi); (I 4) Phaeophyceae (Brown Algae).
The algal fungi, Phycomycetes, are obviously derived from the Green Algae, while the remaining Fungi, the Eumycetes, appear to have sprung from the same stock as the Rhodophyceae.
Algal cells living in association with the animal.