1914] FROMME—AECIDIUM CUP 3 



fertilizations of the type described by Blackman. Olive (22 

 however, reports and figures cases of fertilizations in Caeoma nilens 

 (Gymnoconia inter stitialis) and Triphragrnium Ulmariae that sug- 

 gest the nuclear migrations of Blackman, but are in reality, as he 

 says, simply early stages in cell fusion in which the connecting pore 

 is as yet small. This pore enlarges subsequently and complete 

 union of the cells is accomplished. 



A summary as to the fertilization phenomena in the 1 1 species 

 where fertilization has been described to date is given in table I. 



Besides the question of sexuality, there are a number of unsettled 

 points relating to the morphology of the aecidium cup. Some of 

 these questions were raised by DeBary and have as yet not been 

 completely settled. For example, does the cup enlarge by the 

 addition of new spore chains between those previously formed, or 

 are the new chains added at the lateral borders ? Is the peridium 

 formed from the peripheral chains only, or are the central chains 

 also involved? Do buffer cells similar to those found in the 

 caeomas also occur in the aecidium cup ? 



DeBary (4) stated that the hymenium of Aecidium Berber idis 

 broadens before the cup completely matures, but was unable to 

 determine how this was brought about. He states that the perid- 

 ium arises from the marginal "basidia," and the entire outer chains 

 composed of peridial cells arched over the center of the cup to form 

 a covering over the central spore chains. Richards (27) found that 

 the growth of the hymenium was largely at the periphery and that 

 only rarely were new chains added between those already formed. 

 He states that the peridium is formed from the apical cells of the 

 central spore chains and from all of the cells of the peripheral 

 chains. The peridial cells are first formed at the center, and they 

 are successively formed on all sides of this center until a complete 

 protective layer is formed over the entire mass of spores. Olive 

 (23) agrees substantially with Richards as to the method of forma- 

 tion of the peridium. 



The work of Richards, Blackmax, Christman, Olive, 



Kurssaxow, and others has been summarized by Dittschlag 

 (10). Hoffman (15), Maire (19), and the author (12), and there- 

 fore only the more recent papers will be reviewed. 



