866 Yapp. — Spiraea Ulmaria , Z., and its Bearing on the 
Curator of the Cambridge Botanic Garden, for the trouble he took in 
growing a large number of Spiraeas for me, for the purposes of this paper ; 
and finally to my pupil, Mr. C. M. Green, who is investigating some other 
species of marsh plants, and who has furnished me with information 
concerning their degree of xeromorphy. 
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