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HOP-PICKEK.S OPHTHALMIA. 



and sharper in structure in the mature hop-catkin, because in this 

 fact lies, I believe, the explanation of this disease of hop-pickers, 

 and one of the reasons why it is most prevalent at the hop-harvest. 



Fig. 70. — A microphotograph of the spines upon the bracts of the hop. 



Probable Mode of Production of the Ophthalmia. 



Belonging as the Hiimulus lupuhis does to the same family as 

 the Urtica iirefis, or common stinging nettle, and the order 

 IjRTiCACEiE (which also includes some very severe stinging foreign 

 specimens), and knowing that the hop-plant possesses those 

 sharply-pointed appendages, is it not probable that this painful 

 affection, which is produced immediately and often continues to 

 become worse, is explained by the introduction, either by move- 

 ments of air, by gravitation, or upon the hands of the hop-pickers, 

 of some of those spinous processes of the hop-plant, which, 

 becoming impacted into the conjunctiva or cornea, form the 

 initial cause of the disease ? It is also probable that ujjon them 

 the volatile and resinous matters, etc., of the hop itself, or even 



