x PRACTICAL PURPOSE 275 



from which came diseased silkworms which died young or 

 were useless for the production of silk. Thus the disease 

 passed on by inheritance from year to year. The germs 

 in eggs laid by diseased moths survived ; but those 

 left on leaves, or in the dust, or in the bodies of dead 

 moths, soon perished. Only in the diseased and living 

 eggs was the contagion maintained. 



These things were proved by repeated experiments, and by 

 observations by Pasteur in his own breeding- chamber ; and they 

 made him believe that the disease might be put an end to by the 

 destruction of all diseased eggs. To this end he invented the 

 plan which has been universally adopted, and has restored a 

 source of wealth to the silk districts. 1 Each female moth, when 

 ready to lay eggs, is placed on a separate piece of linen on which 

 it may lay them all. After it has laid them, and has died, it is 

 dried and then pounded in water, and the water is examined 

 microscopically. If " corpuscles " are found in it, the whole of 

 the eggs of this moth, and the linen on which they were laid, 

 are burnt ; if no " corpuscles " are found, the eggs are kept, to 

 be, in due time, hatched, and they yield healthy silkworms. 

 Sir James Paget. 



By the adoption of these methods, arrived at by 

 scientific investigation, a national industry was restored, 

 and the bread of hundreds of poor families was again 

 assured. No wonder that his name is now blessed in 

 the land which profits by the fruit of his splendid 

 discoveries ; yet throughout the whole period of his 

 researches he met with unbelief from practical culti- 

 vators of silkworms, and opposition from merchants of 

 eggs and chimerical remedies for the disease. 



The successful production of Smyrna figs in Cali- 

 fornia is a remarkable' example of the application of 

 scientific knowledge of fertilisation of plants to the 

 establishment of a new industry. The green fig which 

 grows in our gardens usually has no true seeds, and does 



