1 84 DUBLIN NATURAL HISTORY SOCIETY. 



interspersed with a refutation of what Dr. Harvey and myself were so 

 unauthorizedly made to say. 



In re-opening the discussion, it may be well, in the first place, to 

 glance at the statement made at the last meeting, an account of which 

 will be found in ''Saunders's News-Letter" of the 6th.of April, inserted 

 from manuscript furnished by the autHors ; and, in the second place, to 

 state the reasons which lead me to strongly acquiesce in the views of Mr. 

 Bentham. 



The pleasure that botanists feel in making the catalogue of their 

 country's plants as extensive as possible, has (when injudiciously in- 

 dulged) some tendency to warp their judgment ; but truth being their 

 only object, it seems but right that, in addition to their own judgment 

 in the attainment thereof, they should avail themselves of the opinions 

 of other experienced observers, whose opportunity to arrive at a just con- 

 clusion may be greater than their own. One who would positively de- 

 cline to own any master but observation, let his powers of observation 

 be what they may, would Ibe little able to compete with the many 

 talented pupils of Linneus that live at the present day. 



So far as our present knowledge of the two forms of Hymenophyllum, 

 as they occur in Ireland, goes, it is agreed, and never was for a single mo- 

 ment controverted, that they each fairly aspire to the rank of what is 

 popularly called a species. It was not imagined by me that ' ' the peculia- 

 rities and forms of the involucres, as described by the President, went to 

 prove their identity." Far from it. Who would expect to see a cauli- 

 flower turn into a cabbage ? — still less to see our Irish variety called 

 n. Wilsoni, as described by Mr. Andrews, turn into H. Tunhridgense ? 

 But what was stated by me was, that the extraordinary diversity of 

 locality mentioned would, in such instances, and only in such, account 

 for a very great difference in form and habit of growth, and that this 

 mere difference could not for a moment be taken as decisive evidence as 

 to their distinctness ; and it is to be wondered how the President could 

 state that *' locality does not alter the aspects and habits of the plants in 

 question," when, in specimens of his naming, examined in the Hookerian 

 Museum, the aspects and habits of the plants are altered very materially 

 by the localities they have come from ; besides, the point is acknowleded 

 by all botanists. As to the more important diversity in the shape of the 

 involucres, it was not implied that the change from shaded to an exposed 

 position had any affect in altering them, as Mr. Andrews seems to think. 

 It is, however, somewhat difficult, it must be confessed, tobe quite certain 

 what the President means to convey as regards the specific value of this 

 difference, for he at one time says "that the habit of the plant in the same 

 genus must determine specific difference ;" and at another time he seems 

 to attach the chief importance to the diversity in the involucre. But 

 assuming this latter to be, after all, the best ground of distinction, it is 

 the one to which your attention will in a few moments be directed. 



The President asks what difference more striking than those between 

 11. Tunhridgense and II. WiUoni is there between H. hirtellum and //. 

 ciliatum ? My knowledge of exotic forms will not allow me to answer. 



