136 Hillside. 



turn to upright filaments ; these produce spores, which again 

 develop others. 



In a few hours (sometimes less than twenty-four) the 

 fungus grows from spore to maturity, and hence we can 

 readily understand the rate at which the disease spreads ; 

 moreover, as each spore may thus in twenty-four hours pro- 

 duce from sixty to one hundred fresh spores, and these again 

 in proportion, we can readily form an idea of the cause of the 

 rapid spread of the blight. The fungus flourishes best in a 

 moist and warm atmosphere, a dry, hot atmosphere being as 

 fatal to its actual growth as a cold one; 77 F. to 34 F. 

 has been given as the range between which active growth 

 will take place. 



Although the growth of this fungus ceases beyond these 

 limits, the cessation of growth is not accompanied by a 

 cessation of vitality. When the favourable conditions recur 

 every cell of the plant starts anew into life, and recommences 

 its damaging work. 



Its minute size, moreover, makes its spread easy. Dried by 

 the sun, millions of its spores would be in visible in the air, 

 and the wind would waft them for miles and miles, animals 

 may carry them in their fur, or birds in their feathers, and so 

 on. But many remain on or near the spot where they are 

 produced, and no donbt the burning of the affected haulm, 

 and care not to grow potatoes in successive years near an 

 infected spot, together with the use of healthy seed, would do 

 much to stamp out the disease. Nature brings forth in her 

 abundance, and meteorological conditions occasionally aid 

 her to add 'all foison without endeavour, and although man 

 cannot govern these natural tendencies to occasional excessive 

 multiplication, he can adopt measures which will render 



