1896.] ESSAYS. 65 



moniacal carbonate, kerosene emulsion, sulphate of copper solution, 

 etc. There has arisen a complete change in our methods of growing 

 fruits and vegetables. Before going into a description of plant dis- 

 eases let us consider some of the characteristics of fungi in general. 

 The fungi belong, as you all well know, to a low order of plant life, 

 although resembling in their color and mode of life the Indian-pipe, 

 dodder, broom-rape and beech-drops among flowering plants. Thoy 

 either thrive upon the juices of other plants, when they are termed 

 parasites; or else upon decaying organic matter, when they are known 

 as saprophyetes. They contain no chlorophyll or green coloring 

 matter, and hence they are unable to manufacture starch by means of 

 the kinetic rays of the sun out of carbonic acid and water. Instead 

 of giving off oxygen and absorbing carbon dioxide, as is the case 

 with all green plants in sunlight, they continually throw off carbon 

 dioxide, and in this respect their metabolic processes coincides with 

 that of animals. [At this point the speaker briefly referred to the 

 systematic position and mode of reproduction of fungi, which was 

 rendered clear by means of a diagram representing the classification 

 of plants.] 



The total number of fungi in the world, according to Barcardo, on 

 a determinate basis is 40,000 up to 181)2. The number which proba- 

 bly exist in Worcester County is not less than fifteen hundred. For- 

 tunately, however, all the species of fungi are not injurious. The 

 rose alone is subject to 165 species of fungi, although there are not 

 over half a dozen which cause any serious trouble to growers. About 

 200 species of fungi attack our cultivated plants, and are troublesome 

 enough to have received treatment. The number of bacterial diseases 

 so far described affecting cultivated plants is about twenty-five. 



[The essayist then devoted some time to a general description and 

 mode of treatment of about 35 common plant diseases, which was il- 

 lustrated by 23 diagrams representing both their marroscopic and mi- 

 croscopic characters. What follow is a condensed and tabulated ac- 

 count.] 



Cabbage, Turnip, Cauliflower, Etc. 



Club-Foot (Plasmodiophora Brassicte). Occurs as tubercles on the roots. 



Treatment. — Rotation of crops. Also air-slacked lime at tlie rate of 75 

 busliels per acre has sliown beneficial results. 



Potatoes. 



Mildew or Eot (Phytophthora infestaus). Downy appearance on under 

 side of leaf, and rot in tuber. 



Early-Blight (Macrosporium Solani). Small, circular, whitish spots on 

 leaf, usually perforated. 



