28 BOTANICAL GAZETTE [july 



those of the remaining 5 genera are reported as pedicellate. A 

 peridium of the type found in the aecidium cup is to be expected 

 in a deep-seated uredosorus of catenulate spores, but is scarcely to 

 be looked for in a sorus of pedicellate spores, where the supposed 

 protective function is normally performed by paraphyses. 



No central organs ("fertile hyphae") or multinucleated cells 

 were found in any of the species of aecidia studied, and it is there- 

 fore concluded that these do not necessarily occur in aecidia of the 

 cup type. While this by no means precludes the production of 

 multinucleated cells in other species, it is evidence that these are 

 not necessary for the development of the centralized structure of 

 the cup. It is perhaps possible that the multinucleated cells found 

 by Olive in certain cupulate aecidia are the result of multiple cell 

 fusions. The presence of tricellular fusions and trinucleated and 

 quadrinucleated aecidiospores in several of the species I have 

 studied shows that pericellular fusions are rather common in the 

 cup as well as in the caeoma. 



The aecidium cup, from the evidence presented here, is not to 

 be regarded as an organ with a centralized development like that 

 of the ascocarp, as DeBary and others have considered it, but is 

 seen to be merely a remarkably unified colony of individual gameto- 

 phores. The presence of a central organ is no more necessary to 

 the development of the cup than the caeoma. The existence of 

 uredosori with catenulate spores, that arise from sporophytic myce- 

 lium and hence cannot be considered the product of central organs, 

 is further evidence that a seemingly centralized fructification may 

 be developed from a colony. 



The presence of trinucleated spores in various rust sori has been 

 noted by a number of investigators, and there seems to be no ques- 

 tion that such spores, when found in the aecidium or the teleuto- 

 sorus of the micro-forms, are the products of tricellular fusions. The 

 germination of a trinucleated spore would be highly interesting to 

 observe. Hoffman believes that one of the nuclei in trinucleated 

 spores of Endophyllum Semperrivi degenerates, but has no convin- 

 cing proof of this. 



As previously noted, branching basal cells have been found in 

 the aecidium of P. Falcariae bv Dittschlag and in the sorus of 



