148 BOARD OF AGRICULTURE. 



districts in Europe, where the chemical works are continually 

 giving- off traces of hydrochloric acid into the air, vegetation 

 is depressed. The fields do not look bright and healthy. But 

 before the works were compelled by law to save the hydrochloric 

 acid, which is now utilized for the manufacture of bleaching 

 powder, and volumes of this gas rose in the air, the country around 

 the chimneys was black and dead. 



The influence of the sea breeze, carrying with it saline matter, 

 is prejudicial to most plants. There are some plants that 

 withstand the sea air better than others, and the vegetation of the 

 seashore is unlike that of the interior. "At Gorford, near 

 Edinburgh, there is an estate where the trees, on reaching the 

 tops of a wall, are stopped in their growth by the sea breeze, and 

 their tops form an inclined plane proceeding inwards from the wall 

 to the base." 



But the most fruitful cause of disease in plants other than those 

 produced by parasites, is the improper or insufficient supply of 

 plant-food. This portion of the subject has such an exceedingly 

 wide scope, in its practical applications, that the limits of a 

 single lecture would serve only to give you a meagre outline, and 

 faint idea of its importance, and having already occupied so much 

 of your time, I can only give you a hint regarding its general 

 lesson. It is this : A plant in order to be healthy needs food, 

 of proper kind, in suitable quantity. Plants must have this food 

 either from a soil naturally rich enough, or from one which 

 becomes so by manurial applications. Unless they have this food 

 the plants will be feeble, and, if feeble, they cannot resist adverse 

 influences, whether climatic or from parasitic fungi, but they are 

 in a condition to fall an easy prey. You have an exact analogy 

 in the case of man. When an epidemic of a typhus type prevails, 

 the well-fed, healthy man escapes, but the ill-fed, anxious, 

 depressed succumbs. So with plants. Let me refer to an illus- 

 tration in tlio matter of climate. Your great crop is grass, for 

 hay. Tlie amount of hay depends very greatly on the season, 

 whether wet or dry ; if wet, your poorer fields produce con- 

 siderable grass, if dry, very little. Now how is it with your rich 

 mowing fields, sa}^ those good enough to yield 2 to 3 tons per 

 acre ? Will not the experience of every farmer present bear me 

 out in saying, that they do not suffer to an equal extent with the 

 poorer ones ? Tlie crop is light to be sure in a dry year, but 

 unless the drought is excessive, does not suffer so much. 



