THE HOUSE-FLY AS A CARRIER OF POISON GERMS. 367 



THE HOUSE-FLY AS A CARRIER OF POISON GERMS. 



THOMAS TAYLOR, MICROSCOPIST DEPARTMENT OF AGRICULTURE. 



About eighteen months ago, while dissecting the head of a common house- 

 fly, I observed a very minute, snake-Uke animal, a species of auguilula, moving 

 out of the posterior end of its proboscis, which was ruptured. It measured about 

 eighty-one hundredths of an inch in length by about two one-thousandths of an 

 inch in diameter. Subsequently . I determined to ascertain the interior dimen- 

 sions of the suction tube, or proboscis, of the house-fly, for the purpose of com- 

 paring it with the diameter of this parasite. Placing a fly which I had asphyx- 

 iated with naphthaline on a glass slide, and securing it on its back by means of 

 thick gum, I was able to measure the parts and observe all the movements of its 

 proboscis, and found its suction tube to be of sufficient diameter to admit of 

 taking up the spores of cryptogams, trichinae, the eggs of auguilula, or even the 

 auguilulae themselves. 



Noticing a violent commotion in the abdomen of the fly thus operated on, I 

 became convinced that one or more of the auguilulae were present in the abdo- 

 men, and were the cause of the unusual movements observed. On removing the 

 head of the fly, a lively auguilula was seen moving out from one of the ruptured 

 ends of the oesophagus. The animal was quickly secured, and placed under a 

 glass cover in a drop of water, where it exhibited very eel hke or snake-like mo- 

 tions. Shordy a second appeared, when all commotion in the abdomen ceased. 



Of the genus auguilula there are upwards of one hundred known species. 

 They abound in the mosses, in damp earth, and on the green algas found growing 

 on the walls of moss-covered flower pots. Auguilulas are very numerous about 

 the roots of vines, plants, and grasses, and are generally found on decaying moist 

 grain — as wheat — on the bark of trees, and sometimes within fruit while growing. 

 One species of them is found in very large numbers in vinegar. The species I 

 have .found in the house-fly exhibits difl'erent internal structure, in some respects, 

 from any others that I have yet examined.. Whether it is identical with that ob- 

 served in India by Dr. Carter, and more recently by Dr. Leidy, of Philadelphia, 

 to which the name of filaria muscae, and also by Cabold, the name auguilula 

 muscae has been applied, I cannot determine in the absence of detailed descrip- 

 tions and drawings representing members of that species. 



The facts above stated suggested to my mind the importance of instituting a 

 series of experiments to ascertain whether house-flies might not be carriers and 

 distributors of germinal virus. I have found in the proboscis of a single house- 

 fly thirteen of the animals already mentioned in a perfectly developed condition, 

 and on the thorax of another I have found sixteen living parasites of the genus 

 acarus. It therefore seems quite possible that other microscopic organisms might 

 be taken up by the house-fly, and again deposited where they might prove dan- 

 gerous to man. This might easily happen in the case of trichinae, Ss trichnosed 



