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IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



nated. One specimen showed the Hfe of urediniospores on leaves in 

 a dry, warm Hving room to be 55 days. A rusted mammoth clover 

 plant retained the uredinial stage in the greenhouse all winter until 

 April 2 when it was entirely dead, probably due to the rust as others 

 not rusted were in a healthy condition. 



Urediniospores mounted in lacto-phenol and examined after 

 standing one week showed plainly 5 and 6 germ pores scattered. 



Fig. 87. — These germ tubes averaged 4 microns in diameter. Taken from a 

 transplanted plant, December 12, 1918. Drawn after standing twenty-four hours 

 in water. Number 4 shows a germ tube branching. 



The number of germ pores varied from 5 to 7, thus following the 

 rust on red clover in this respect. The spores are ecinulated and 

 fifty projections were counted on one side of one spore. The 

 spores are shown in figure 88. 



The measurements of the spores varied slightly from the ure- 

 diniospores on red clover but the variation is no more than could 

 be expcctc'fl bctwci-n the ineasuromcnls of anv two spore samples. 



