152 The hish Naturalist. August, 



B. Effects of spread of hiq/icr state of civilization or extension 

 of i7idustrics, etc. 



*(a) Drainage and reclamation of land (agricultural). 

 *(Ij) Cultivation (agricultural). 

 *{c) Deforestation or planting (agricultural). 

 *{d) Smoke and injurious gases, &c. (generally in- 

 dustrial). 

 *{e) Building operations, and demolition of buildings or 



mud walls (industrial), 

 (y) Sport, golf links (recreative). 

 *{o) Hawking (commercial). 



*{/i) Collecting (amateur rapacity ; scientific indis- 

 crimination). 



Minor Causes. — In addition to the foregoing main causes 

 contributing either to the extermination or diminution of 

 these plants, either locally or over extensive areas (noticed 

 under " Effect "), there are a number of minor causes at work 

 that at different localities produce marked effects. These are 

 principally : — 



*i. Burning of furze and heather. 

 2. Road-scraping and cutting down of roadside hedges, 

 scraping out of ditches and the throwing of their 

 contents upon the ditch banks. Paving, &c., of foot 

 paths. 

 *3. Action of steam rollers, motor cars, &c., on roadside 

 plants. 

 4. Pollution of waters b}^ chemical and d3'eing works. 

 *5. P'ormation of railway embankments, causing barriers 

 to the dispersal of spores, &c., or the concentration 

 of plants produced therefrom in unsuitable habitats. 

 6. Clearing away of .stones from fields, especiall}^ cal- 

 careous pebbles and plants, detrimental to the dis- 

 tribution of lyichens and some Mosses and Hepatics. 

 ^■j. Clearing away of undergrowth in woods, &c., depriving 



mosses of .shelter and moisture. 

 ■^8. Cutting out ofbogs for peat or digging "turves" for fuel. 

 *(). IvOwering of levels of lakes. 



10. F'ouling of soil by sea-birds. 



11. Dressing trees with insecticides and lime-wa.shing ; 



destructive to mosses and lichens. 



