Good cytological evidence has been adduced in favor of both theories, but further investigation is necessary before any definite conclusion can be arrived at.
The cytological evidence for this appears to be made stronger for animal than for plant cells.
Cytological details of nuclear behaviour among the lichens are, however, difficult to obtain owing 'to the slow growth of these forms and the often refractory t' nature of the material in the matter of preparation for microscopical ex amination.
The cytological details of development of the perithecia are not well known; most of them appear to develop their ascogenous hyphae in an apogamous way without any connexion with an ascogonium.
It is by means of the cytological evidence, however, that this problem will finally be solved.