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W. L. WATERHOUSE. 



of the plants. The straw and both plants were sprinkled 

 with water daily for a week. 



No case of rust infection occurred. This negative result 

 was expected, because the same method had been tried 

 and had failed in England where better conditions for 

 infection — a higher humidity — prevailed, 



A successful method which had been worked out at 

 South Kensington was then tried. It was there noted that 

 more abundant teleutospore germinations appeared to be 

 obtained by leaving the spores intact in the sori than by 

 separating the teleutospores by scraping them off the straw. 



Fragments of the straw on which teleutosori were present 

 were soaked in tap-water for five minutes. The barberry 

 plants were sprinkled with water and the soaked fragments 

 of straw placed on young leaves. The whole shoot was 

 then enclosed in a glass cylinder (a lamp chimney) which 

 was then lightly packed with cotton wool at the top and 

 bottom, and then supported by a stake. (Plate XIX, fig. 1.) 

 A very humid atmosphere was thus maintained within the 

 cylinder. The shoot was kept enclosed for 24 hours in some 

 cases, and for 36 hours in others; there was no discernible 

 difference in the results. 



In each case, after four to five days, discoloured spots 

 appeared on the upper surfaces of the inoculated leaves. 

 In addition, in some cases, dead areas occurred, mainly at 

 the edges of the leaves. The causal agents were not deter- 

 mined, but similar necrotic areas were also present on 

 control shoots which had not been enclosed in the cylinders. 

 It appears, therefore, that the teleutospore inoculation 

 was not the cause of the necrosis. 



After 8 to 10 days yellowish spermagonia became visible 

 on the upper surfaces of the leaves. Aecidia were produced 

 on the lower surfaces 4 to 5 days later. Aecidiospores- 



