For the past three years I have experimented, intentionally and accidentally, and produced all the earlier symptoms of hay fever, severe coryza, etc., by the direct application of the pollen to the mucous membrane of the nose. For instance, last week, I wished to observe the pollen of another variety of Ambrosia "trifolia" or giant rag-weed. I gathered a few heads and put them in water to ripen, then examining the dust pollen under a microscope, and not taking care to prevent it flying in the air, suffered all that day with coryza. I tried the experiment two years ago in the same way, by ripening it prematurely, while I was still well and unaffected, and with the same serious consequences. After going to the White Mountains, and being entirely recovered, I found a small patch of rag-weed, and with another victim made the same experiment, and equally successfully, so successfully that we suffered several days.