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pathologists using the names of the human pathologist and the physician. 
They speak of “epidemics” and “endemics” among plants—those terms 
etymologically refer to people, meaning “upon the people’ and “among the 
people”. It seems rather incongruous to use such terms for diseases upon 
or among plants. But it is facts, not words, that scientists are after. 
Then there occur such names as chlorosis, icterus, atrophy, necrosis, and 
even cancer and consumption. 
Plants are afflicted with diseases due to bacteria, to fungi (even to 
higher, flowering, plants), to animal and vegetable parasites of all kinds, 
to mites and worms, just as human beings. But, perliaps needless to say, 
the species are different. Although some of the common names current 
among physicians are used, vet the scientific names are wholly different. 
Another thing that impresses one on going through the books on plant 
pathology is the importance attached to cleanliness, as cleanliness apout 
the orchard, destroying dead branches and leaves and keeping the ground 
and trunk clean, the necessity for spraying and fumigating, measures that 
physicians long ago leariied but which the people are slew to adopt. Thai 
cities need as careful attention as orchards seems to be known to but few 
ef the people. The old farmer must be told why his orchard does not 
flourish, why trees are sickly and ultiniately die, just as many a com- 
munity must be told why its people are sickly and why there is race 
suicide. 
One day while botanizing I came across a field thickly overgrown with 
Iron Weed and Vervain. At one end it was wet and swampy, with pools 
of water. The farmer, who was plowing, overtook me. We engaged in con- 
versation. JI asked him why he allowed those weeds to grow. ‘The cows 
like weeds; they brush off mosquitoes and flies.” Te thought this sufficient 
reason for allowing weeds to grow. I pointed out how flies breed in his 
manure pile and that by giving a little attention the number of flies could 
be greatly reduced; that mosquitoes breed in wet places, as at the end of 
the field, and that with a little drainage the mosquito pest could be pre- 
vented; that with flies and mosquitoes absent there would be no need for 
the weeds; with fewer flies the cows wasted less energy in switching them 
and would give more milk; and in the absence of blood-sucking mosquitoes 
would gain in flesh. In the absence of weeds there would not be a con- 
stant cloud of seed blowing on to his cultivated fields and on to those of 
his neighbors. 
