The Biotic Relationship of Anthoceros and Phaeoceros to Certain Cyanophyta

When the Nostoc isolates entered into thalloid cavities of Anthoceros and Phaeoceros and produced the typical globose endophytic colonies and/or when the algal isolate grew Pare Pie ponents of the mucilaginous thalloid cavity.The presence of blue-green algae in thalli of Anthoceros was first reported by Hofmeister (1862) who thought the dark, blue-green, roundish masses in the thallus to be gemmae.However, careful investigations by Leitgeb (1881) showed that they were Nostoc colonies within the mucilaginous Anthoceros cavities.He reported that the endophytism is effected by the movement of free Nostoc hormogonia through slit-like openings into the mucilage cavities.Once within the cavities the hormogonia grow into globular colonies.The presence of Nostoc within the thallus causes an increased, attenuated growth of the cells surrounding the cavity.According to Campbell (1918) and Parihar (1961) the "host" cells produce tubular filaments which ramify through the algal mass and become so interwoven with it that sections appear as loose parenchyma with Nostoc filaments occupying the interstices.The writer can confirm their observations.Pierce (1906) reported that the presence of the endophytic blue-green alga was not necessary for growth of the gametophyte, and that in fact thalli grown 'Rewritten portion of a thesis submitted in partial fulfillment for the Doctor of Philosophy degree at the University of Texas.*I wish to express appreciation to Professor H. C. Bold for his assistance and to the National Science Foundation (Grant No GB-313).