18 BOTANICAL GAZETTE . [july 



this 



term 



cell" should be restricted to indicate the cell in which the transition 

 from the uninucleated to the binucleated condition occurs. 



In addition to the normal cell fusions between two gametes a 

 number of cases of triple cell fusions were found. Two of these are 

 illustrated in figs. 7 and 18. Fig. 7 is of P. Claytoniata and fig. 18 

 of Ur. Caladii. In both of these cases the three fusing cells lie in 

 separate hyphae. In one or two other cases found two of the 

 gametes came from the same hypha. Similar cases have also been 

 found in Mel. Lini (12, fig. 18). The trinucleated fusion cells 

 resulting from a fusion of three cells may function as basal cells. 

 In this case the three nuclei divide simultaneously (figs. 12, 13), in 

 the same manner as those in the binucleated fusion cells , and tri- 

 nucleated aecidiospores and intercalary cells are formed. In fig. 9 

 a trinucleated aecidiospore initial cell has been abstricted from a 

 trinucleated basal cell. The basal cell appears two-legged, but it 

 is probable that one of the legs has been cut off in the section. 

 Mature trinucleated aecidiospores are quite common in P> Clay- 

 toniata; several are often found in one section of a mature cup. 

 They are somewhat less common in Ur. Caladii and P. Viola e and 

 are only rarely met with in the other forms. 



Quadrinucleated aecidiospores were also found, but in fewer 

 numbers than the trinucleated ones. A chain of quadrinucleated 

 cells is shown in fig. 14. The apical aecidiospore of the chain con- 

 tains 4 nuclei, while none are visible in the intercalary cell below it. 

 Only 3 nuclei appear in the next aecidiospore, but the subtending 

 intercalary cell is distinctly quadrinucleated. The lowest cell of 

 the chain is probably an undivided aecidiospore initial cell. The 

 4 nuclei are arranged serially in the long axis of the cell. The chain 

 was cut off at this point in the section and could not be located in 

 adjoining sections. While no four-cell fusions nor four-legged basal 

 cells were found, there can be little doubt that these occur in the 

 cupulate aecidia as well as in the caeoma of Mel. Lini (12). 



Many of the fusion cells formed undoubtedly do not function as 

 basal cells for lack of space. Those in the upper part of the gametic 

 tissue, immediately beneath the pseudoparenchyma, are more favor- 



