REPRODUCTIVE ORGANS 277 



they are more advanced than these judging from the thalline wall that is 

 present in some genera and also from the half-open disc at maturity. The 

 latter feature has influenced some systematists to classify the whole subseries 

 among Cyclocarpineae. The thallus, as in Sphaerophorus, reaches a high 

 degree of fruticose development ; in other genera it is crustaceous without 

 any formation of cortex, while in several genera or species it is non-existent, 

 the fruits being parasites on the thalli of other lichens or saprophytes on 

 dead wood, humus, etc. These latter both parasites and saprophytes 

 are included by Rehm 1 and others among fungi, which has involved the 

 breaking up of this very distinctive series. Rehm has thus published as 

 Discomycetes the lichen genera Sphinctrina, Cyphelium, Coniocybe, Ascolium\ 

 Calicium and Stenocybe, since some or all of their species are regarded by 

 him as fungi. 



Reinke 2 in his lichen studies states that it might not be impossible for 

 a saprophytic fungus to be derived from a crustaceous lichen a case of 

 reversion but that no such instance was then known. More exact studies 3 

 of parasymbiosis and antagonistic symbiosis have shown the wide range of 

 possible life-conditions, and such a reversion does not seem improbable. We 

 must also bear in mind that in suitable cultures, lichen hyphae can be grown 

 without gonidia: they develop in that case as saprophytes. 



On Reinke's 2 view, however, that these saprophytic species, belonging to 

 different genera in the Coniocarpineae, are true fungi, they would represent 

 the direct and closely related ancestors of the corresponding lichen genera, 

 giving a polyphyletic origin within this group. As fungus genera he has 

 united them in Protocaliciaceae, and the representatives among fungi he 

 distinguishes, as does Wainio 4 , under such names as Mycocalicium and 

 Mycocon iocybe. 



If we might consider the saprophytic forms as also retrogressive lichens, 

 a monophyletic origin from some remote fungal ancestor would prove a more 

 satisfactory solution of the inheritance problem. This view is even supported 

 by a comparison Reinke himself has drawn between the development of the 

 fructification in Mycocalicium parietinum, a saprophyte, and in his view a 

 fungus, and Chaenotheca chrysocephala, a closely allied lichen. Both grow on 

 old timber. In the former (the fungus), the mycelium pervades the outer 

 weathered wood-cells, and the fruit stalk rises from a clump of brownish 

 hyphae; there is no trace of gonidia. ChaenotJuca chrysocephala differs in the 

 presence of gonidia which are associated with the mycelium in scattered 

 granular warts; but the fruit stalk here also rises directly from the mycelium 

 between the granules. The presence of a lichen thallus chiefly differentiates 

 between the two plants, and this thallus is not a casual or recent association; 

 it is constant and of great antiquity as it is richly provided with lichen-acids. 



1 Rehm 1890. 2 Reinke 1894. 3 See p. 260. 4 Wainio 1890. 



