Algal cells living in association with the animal.
Some forms, however, such as " Sarcina," have their algal analogues in Palmellaceae among the green algae, while Thaxter's group of Myxobacteriaceae suggests a relationship with the Myxornycetes.
It may be regarded as derived from a wholly dependent sporogonium not unlike that of some of the simpler Bryophyta; the latter are assumed to have arisen from primitive Algal forms, in which, as the first step in the interpolation of the second generation in the life cycle, the fertilized ovum gave rise to a group of swarm spores, each of which developed into a new sexual plant.
(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.