PORTER — Organs of the Common Corticolous Ramalinac. 31 



The remedies for lichen-growth on fruit trees may be summarized as 

 follows : — 



1. Scraping off the outer hark scales and painting with lime-wash. 



2. Spraying with Bordeaux mixture. 



3. Spraying with 5 per cent, soda solution to which 3 to 4 per cent, carbolic 

 acid has been added. If the percentage of acid is increased, the spraying must 

 be done in winter or the buds will be injured, though the increase has the 

 merit of removing scale and other insects. 



VI.— SUMMAKY OF CONCLUSIONS. 



1. The thallus of the Eamalinae consists of cortex, gonidial layer, and 

 medulla. 



2. The cortex consists of longitudinally arranged hyphae whose apices 

 turn outwards to the surface. 



3. Differentiation of the inner and outer cortices, and pseudoparenchy- 

 matic appearance of the former may be produced by suitable reagents. 



4. The attachment organs are strands of closely woven hyphae, 

 longitudinally arranged, and continuous with the cortical tissue. 



5. They penetrate the periderm by cracks or lenticels, and by wedge-action 

 cause extensive splitting. 



6. They give rise to branches in all directions. 



7. From these horizontal branches, or from the superficial soredial layer, 

 or from both acting in conjunction, arise new plants. 



8. These organs may penetrate the living tissues as far as the new wood, 

 causing direct injury to the tree. 



9. They also cause hypertrophy of the peridermal tissue, and erosion of 

 the wood by ingrowths of hypertrophied tissue. 



In conclusion, the author's thanks are due to Dr. 0. V. Darbishire, of 

 Bristol University, for proposing the subject under consideration, and for 

 the loan of otherwise inaccessible literature; to Professor II. W. Phillips, of 

 the University College of North Wales, Bangor, for advice and encourage- 

 ment in the practical investigations; and to Professor M. Hartog, of 

 University College, Cork, for criticisms and suggestions as to the arrangement 

 of the work. 



