Plate 4. — Effect of mycorrhizae on plant growth. "Two beds 

 of seedlings of a Himalayan species of pine, Pinus longifolia, 

 from the same sowing in northern Rhodesia. Further bed inocu- 

 lated with soil containing a mycorrhiza-forming fungus for the 

 species from a vigorous plantation of this pine at a station in 

 Southern Rhodesia 1000 miles distant; nearer bed untreated." 

 (From a photograph kindly loaned by Dr. R.wxf.r). 



