26 FOKESTS, WOODS, AND TEEES 



media containing minute particles of carbon. Turpentine 

 and allied substances, used in minute quantities as media, 

 greatly increase the number of carbon particles that are 

 swallowed by the leucocytes. In a dilution of 1 : 100,000 

 an increase was found of 2 4' 7 per cent. In the presence 

 of turpentine the percentage of the white cells that have 

 taken in carbon is greater than in the case where no 

 turpentine is added. This explains the remedial action of 

 a subcutaneous injection of turpentine in the treatment of 

 pneumonia in horses, as minute quantities of the turpentine, 

 dissolving in the lymph of the tissue spaces and afterwards 

 entering the blood circulation, promote the phagocytic 

 power of the white corpuscles in the lung. 



Hamburger says that the cause of the remarkable in- 

 fluence of a sojourn in high mountain regions on metabolism, 

 on sleep, and on the state of the mind is entirely unknown. 

 It has been proved that these phenomena are not due to the 

 altitude as such, for in balloons they do not occur, nor are 

 they found in all mountain regions, but only in those parts 

 with coniferous woods. He thinks that it is due to the 

 stimulating action of the odour of resin, turpentine, etc., on 

 the nerve cells. The exhalations of the trees reach the 

 lungs by inspiration, and are transported by the blood 

 current through the whole body, and in consequence to the 

 nerve cells, thus promoting metabolism, sleep, etc. May 

 not such vapours, however, brought directly into contact with 

 the white blood corpuscles in the lungs by every breath 

 taken in, stimulate these to vigorous attacks on the tuber- 

 culosis bacteria ? 



It is probable then that Pliny was right in his view of 

 the curative influence of pine forests ; but at the same time 

 we must not forget the injurious effect of screens of trees 

 and shrubs close to a dwelling in blocking out sunshine 

 and in stagnating the air. 



As forestry work, varied in character and in muscular 

 effort, can be carried on out-of-doors in all seasons, it is now 

 utilised in the sanatorium treatment of consumptive patients. 

 This is one of the features of the interesting afforestation 



