58 



conglomeratus, with the ovencliyma of the pith of Juncns 

 bufonius. The constant diflference of size in the cells is 

 remarkable sometimes when their form and contents remain 

 the same. If you examine them in Hymenophyllura 

 Wilsoni and H. Tunbridgense, you will perceive this 

 difference at once, and very likely then dissent from the 

 views of those eminent botanists who regard these two 

 pretty ferns as but one species. To the same effect is 

 the uniformly smaller size of the pollen-cells in Lotus 

 major than in L. corniculatus. By the singular largeness 

 and roughness of the same cells in Ranunculus arvcnsis, 

 this species is distinguished from its nearest allies, and other 

 curious cell-differences, either of form or size, occur in dif- 

 ferent sections of this genus, and indeed of many other genera. 



But still more striking examples occur as regards eithei 

 the presence or absence of raphidian cells. Thus, e.p., if 

 the question be to discriminate between a Balsam, Bed- 

 straw, or Willow-herb— species belonging to the orders 

 Balsaminaceae, Onagraceie and Galiacese — and any of the 

 plants in the alliances of those orders, mere siiapeless 

 fragments of the leaves or stems, or other parts, without the 

 slightest aid from the recognized characters in systematic 

 books, would, as already explained, be quite sufficient for 

 the purpose. 



Of the validity of this character numberless examples 

 might be added ; one more will suffice now. Having 

 proved the facts as regards several orders in our own 

 Flora, I extended the inquiry to all the exotic plants avail- 

 able, and never could find any exception to the character of 

 Onagraceae, e.g., as a raphis-bearing order ; when at length 

 an apparent exception turned up in Montinia. However, 

 on subsequent inquiry this genus, though placed by Lindley 

 and other eminent botanists in the order OnagraceiE.proved 

 to be no member of it, but rather to belong to the 

 Saxifrages, with which its cell-structure better agrees ; and 

 thus a seeming exception became an excellent proof of the 

 rule. 



