590 COMPARATIVE MORPHOLOGY OF FUNGI 



Maleness in the red algae is expressed in the form of antheridia producing 

 spermatia. These bodies function primarily in fecundation and, in certain 

 groups, secondarily in the cell fusions subsequent to fertilization. In the rusts 

 maleness has persisted as shown by the development of spermogonia with their 

 spermatia which are primarily functionless in the absence of an egg apparatus. 

 This condition is associated with the occurrence of accessory cell fusions culmi- 

 nating, in Gymnoconia, in nuclear fusions in the teliospore. 



A long-cycled rust becomes short cycled without losing the power to develop 

 the basidium, which may be formed without previous caryogamy, in which case 

 there is no necessity for meiosis. Therefore the number of cells in a phragmo- 

 basidium need not always be four. The presence of some male element exer- 

 cising its secondary function indicates maturity, and plasmogamy will occur, while 

 inhibition of such a development is shown by the absence of plasmogamy. 



The Brefeld school (Brefeld, 1889; Tavel, 1892; Christman, 1907; 

 Olive, 1908, 1911; in part E. Fischer, 1912) proceeds from the hypothesis 

 discussed on page 421, that the basidium is a conidiophore which has 

 become constant in form and spore number. Thus it connects the Ure- 

 dinales and the Auriculariaceae with the Zygomycetes and attempts to 

 elucidate this by a comparison between Chaetocladium and Endophyllum. 

 The zygospores of Chaetocladium and the aeciospores of Endophyllum 

 are both the direct product of a sexual act and both germinate normally 

 with a conidiophore, which in Chaetocladium is indefinite and in Endo- 

 phyllum is fixed as a basidium. The remaining spore forms were developed 

 succesively de novo. This conception offers the advantage that it draws 

 a direct parallel for the plasmogamy occurring between two basal cells 

 and for the fusion cell itself: functionally the fusion cell is a zygospore 

 formed by the copulation of gametangia which have become uninucleate. 

 The difficulty is that it requires the basidium to be a stabilized conidio- 

 phore which, as has been shown on page 421, is contradicted by important 

 cytological considerations. Therefore, between the organization of the 

 Zygomycetes and of the Uredinales, there lies such a broad gulf that this 

 conception would be untenable. 



A third solution of the problem consists in the connecting of the Ure- 

 dinales to other Basidiomycetes, particularly the Auriculariaceae. This 

 idea was first expressed by Moller (1895) and further developed by 

 Jahnchen (1923) and Neuhoff (1924). As a starting point one might 

 consider Auriculariaceous forms, as Eocronartium muscicola, which possess 

 micro- and macroconidia. The microconidia, cut off singly on unicellular 

 sterigmata, are the ancestors of the pycniospores. The macroconidia 

 arose singly from a mother cell which divided into a spore and a stipe cell, 

 something as the initial cells of Phragmidium Potentillae-canadensis at the 

 present time. With the transition to endoparasitism and the increasing 

 difficulty to rupture the tissue of the host, the sporophores collect into 

 sori. 



