These observations of Elenkin and Danilov have been proved to be erroneous by Paulson and Somerville Hastings[231]. They examined the thalli of several lichens (_Xanthoria parietina_, _Cladonia_ sp., etc.) collected in early spring when vegetative growth in these plants was found to be at its highest activity. They found an abundant increase of gonidia within the thallus, which they regarded as sporulation of the algae, and the most careful methods of staining failed to reveal any case of penetration of the gonidia by the hyphae. Nienburg[232] has published some recent observations on the association of the symbionts. In the wide cortex of a _Pertusaria_ he found not only the densely compact hyphae, but also isolated gonidia. In front of these latter there was a small hollow cavity and, behind, parallel hyphae rich in contents. These gonidia had originated from the normal gonidial zone. They were moved upward by special hyphae called by Nienburg “push-hyphae.” After their transportation, the algae at once divide and the products of division pass to a resting stage and become the centre of a new thalline growth. A somewhat similar process was noted towards the apex of _Evernia furfuracea_. Radial hyphae pushed up the cortex, leaving a hollow space over the gonidial zone. Into the space isolated algae were thrust by “push-hyphae.” In this lichen he also observed the penetration of the algal cell by haustoria of the fungus. He considers that the alga reaps advantage but also suffers harm, and he proposes the term _helotism_ to express the relationship. An instructive case of the true parasitism of a fungus on an alga has been described by Zukal[233] in the case of _Endomyces scytonemata_ which he calls a “half-lichen.” The mature fungus formed small swellings on the filaments of the _Scytonema_ and, when examined, the hyphae were seen to have attacked the alga, penetrating the outer gelatinous sheath and then using up the contents of the green cells. It is only after the alga has been destroyed and absorbed, that asci are formed by the fungus. Zukal contrasts the development of this fungus with the symbiotic growth of the two constituents in _Ephebe_ where both grow together for an indefinite time.