88 Scientific Proceedings, Royal Dublin Society. 



red, while B. cuspidata gives no reaction. In order to see if both species 

 were present on the Howth shores, and if possible to find out tlie conditions 

 under whicli they grow, a large series of Ramalinas was collected at various 

 parts of the south and south-west coasts from both zones, and treated with the 

 potash solution. 



The results showed. that, among the lower Ramalinas, those that gave no 



reaction when treated with potash (that is, Ramalina cuspidata of the floras), 



grew chiefly between Sutton and Old Boat-house, inside the shelter of Dublin 



Bay, and were extremely scarce beyond Drumleck Point ; while the Ramalinas 



in which the medulla turned first yellow and then red under the potash 



(S. scopulorum) were very scarce near Sutton, but became more abundant 



as the coast-line approached the open sea until, at Lion's Head and the Baily 



peninsula, the most outstanding parts of the coast, they were the only 



Ramalinas met with. The upper Ramalinas were less responsive to the 



potash treatment, but here and there tufts were met with at all levels on the 



cliffs at Eed Rocks, at Drumleck Point, and at other places that changed 



colour. On the east coast also the majority of the specimens from the upper zone 



gave no reaction. These results tally with Olivier's account (21) of the habitat 



of R. cuspidata, which species he describes as growing further from the sea 



than R. scopulorum, and as sometimes extending inland for a considerable 



distance. Crombie (4), too, gives the habitat of R. cuspidata as " rocks and 



boulders in maritime districts, rarely on hills at a distance from the sea." 



There are, however, those specimens in which tlie reaction was indecisive, the 



cortex turning faint yellow, or a rich coppery colour, while the medulla 



remained unchanged, or showed only a very faint stain. How are these 



specimens to be classified ? Under R. cuspidata or R. scopulorum ? As already 



stated, this test with potash is the only means of distinguishing the two species ; 



but since it is not associated with anj' differences in form or in microscopic 



structure, it seems to be a very unsatisfactory character on which to found a 



species. Weddell disregards it, and includes R. cuspidata under R. scopulorum. 



Harmand (6), in discussing the value of the reaction tests, considers that at least 



they have " une valeur documentaire, et qu'ime flore descriptive ne peut les 



passer sous silence"; while Zopf (32) lias found in R. cuspidata ouspidatic acid 



(CieHjoOio), an acid only met with in this species, and in R. seojmlorum 



scopularic acid (CigHisOg), soluble in potash, giving yellow and then red 



colours on solution, and only found in the latter species. 



It would appear from the experiments made on the Howth Ramalinas 

 that the change in colour produced by tlie potash is in some way due to the 

 action of the salt water, as it seems to vary in intensity according as the 

 Ramalinas are often or seldom wetted by the sea. The first parts to take the 



i 



