The malady spread from year to year, until in 1858 the amount 

 of silk produced was diminished to one-third of that which had 

 been made previous to 1853. In brief, a microscopic fungus, 

 preying upon the silk- worm and causing its destruction by thou- 

 sands, prostrated the industries of the city of Lyons, and plunged 

 its working class into idleness and want. What the total loss 

 was, could not be determined, as all classes of industry suffered, 

 but the direct loss was estimated at ;^ 2 5 0,000,000. 



The fact that the insects mentioned by Dr. Hagen exist in 

 great numbers, is most favorable to the rapid spread of any dis- 

 ease that may appear among them, and the remedy proposed, 

 should it work at all, would probably prove powerful, rapid and 

 insidious. The spread of the potato rot, Peronospora infestans, 

 over the whole of the British Isles within two years after its intro- 

 duction, is an example of how rapidly and thoroughly spores may 

 permeate any region when all the conditions are favorable to their 

 growth. 



In examining the question as proposed by Dr. Hagen, many 

 facts must be taken into account before deciding upon the prob- 

 able results. It must be remembered that the air is at all times 

 charged with the spores of fungi. Dr. Cunningham found that 

 " spores and other vegetable cells are constantly present in atmos- 

 pheric dust, and usually occur in considerable numbers ; the 

 majority of them are living and capable of growth and develop- 

 ment."^ 



Dr. S. M. Babcock, in studying the chemical changes of cheese 

 during the curing process, finds it impossible to avoid mold in the 

 curd except by heat and anaesthetics (ether and chloroform). He 

 states that the spores seem to be in the very milk used in the 

 experiments. 



In the Botanical Laboratory, at Cornell University, where 

 molds and yeast are cultivated at certain times for experimenta- 

 tion, the air soon becomes charged with .spores. 



Growing in the same laboratory and rooms directly connected 

 with it, are plants which require constant care lest they be over- 

 run with their several insect pests. No disease appears to have 

 attacked these insects. It may be said that they do not feed upon 

 the yeast, and for this reason escape. It is not necessary that the 



' " Microscopical Examinations of Air," from the " Ninth Annual Report of the 

 Sanitary Commissioner." Calcutta, 1872. 



