DISSEMINATORS OF DISEASE 59 



been suspect. The microscope reveals much, and the 

 art of bacterial culture now explains how it is true that 

 the superabundant creature, which has persistently 

 followed civilised man into every quarter of the globe, 

 has ever had a share in conveying contagion beyond 

 that of any other household pest. 



That the house-fly is bred in filth matters not much. 

 After emerging from the puparium its first voidance of 

 faecal matter may be contaminated with live baneful 

 germs, but it voids itself before its first flight. Having 

 six legs it stands upon two pairs, whilst with the other 

 pairs, at one time the front pair and at another time the 

 hind pair, it works frequently and vigorously at 

 brushing and stroking down every part of its body. 

 Though it starts its new life quite a wholesome new- 

 born creature, and though it must be credited with 

 being a most assiduous remover of dirt from its own 

 body, yet from the human point of view its subsequent 

 life is a persistently disgraceful career. 



It is the evil course of the newly-hatched and self- 

 cleaned fly not to restrict its diet to the honey of 

 flowers, as do some of its relations. Its food includes 

 excrement, sputum, and eveiy kind of putrefying 

 organic matter likely to be swarming witlr micro- 

 organisms of a character deleterious to humanity. It 

 is certain that, when only a few days old, a fly will 

 practically abound internally and externally (on the 

 feet) with dangerous germs, as amply proved by 

 methods of laboratory culture . As it feeds, it walks 

 over the food ; and the hairy joints of its feet, when 

 microscopically viewed, appear conspicuously liable to 

 carry germs in spite of frequent attempts at self- 



