350 



COMPARATIVE MORPHOLOGY OF FUNGI 



chambers extend into the fructification (Fig. 234, b) and are nearly- 

 enclosed. Even in these highest forms, the meridianal folds are 

 bound by transverse ones in a regular network which morphologi- 

 cally is equal to that of the higher Gasteromycetes. As Morchella 

 esculenta can discharge its ascospores to a height of several centimeters, 



one might conclude that the hymenia in the deeper 

 chambers would shoot against each other; it seems, 

 however, that the difference in temperature and 

 dampness between the interior of the chambers 

 and the outer world causes currents of air which 

 bear the spores outward (Falck, 1916). 



Discomycetous Lichens. — Herewith we have 

 ended the discussion of the Pezizales. As numer- 

 ous representatives of this order have united with 

 algae to form lichens and as these Discomycetous 

 lichens play an important part in the derivation 

 of the Ascomycetes from the Florideae, we will 

 add a short discussion of the sexual relations of 

 this group. We will limit ourselves here expressly 

 to the ontogeny of the more important types and 

 for all the remaining questions refer to the works 

 of A. L. Smith (1921) and Tobler (1925). The 

 previously investigated Discomycetous lichens 

 have in common with the higher Pezizales, first, 

 that their carpogonia do not proceed directly from 

 the vegetative hyphae of the hypothecium but 

 from deeply staining primordial hyphae, the so- 

 -Collemacris- called generative hyphae. Further, a large num- 

 pum. Development of sex- ber of their genera (Saettler, 1914, mentions 24), 

 ual organs, a, tnchogyne ^ e man y Pezizales, possess helical or tangled 



which has copulated with a ... . . . 



conidium," the septa have ascogoma with tnchogynes which transitorily 



project into the open. In the Discomycetous 

 lichens, however, antheridia similar to those of the 

 Pezizales are unknown. As far as there is a sex- 

 ual act, it must occur according to the Ascobolus 

 carbonarius type or be replaced by deuterogamy. 



The fact that numerous lichens possess pycnia and that their trich- 

 ogynes occasionally secrete a slimy substance by means of which they 

 can hold fast the pycniospores (spermatia) brought by the rain, suggests 

 the Ascobolus carbonarius type. Actually one sees conidia (spermatia) 

 clinging fast to the trichogynes, and in Collema crispum it has been 

 demonstrated that between the trichogyne tip and the conidium appears 

 an open communication whereupon the septa of the trichogyne disappear 

 (Fig. 235). This allows one to conclude that the conidial nucleus 



already dissolved, b, asco- 

 gonium with trichogyne, 

 several conidia clinging to 

 the free end of the latter. 

 (After Baur, 1898.) 



