154 THE GROWTH OF GROUPS 



ears belongs especially to the green-bottle flies. Descrip- 

 tions of the fly are not always recorded in cases of myiasis. 

 Within the years 1909-10, ten cases were described or 

 mentioned in the Indian Medical Gazette, in three of these 

 cases the fly was hatched out for identification. In 

 two cases the insect was identified by a competent ento- 

 mologist as a species of Pycnosoma, the third case was 

 accompanied by a sketch and description of the insect, 

 which was certainly a green-bottle fly. The three cases 

 are each from a different province of India, being separated 

 from one another by many hundreds of miles. In some 

 other parts of the world, in South America and the southern 

 United States for example, myiasis appears to be more 

 common and is definitely ascribed to a green-bottle fly 

 with three dark lines on the thorax, which is spoken of 

 as Lucilia by some writers and Compsomyia by others. 

 Myiasis is scarcely known in Europe, but there is an in- 

 teresting case of Lucilia attacking living sheep at Am- 

 sterdam. Here there was a considerable outbreak of 

 the disease, if we may so call it, which was explained in 

 the usual manner on the supposition that the hostile 

 organism was imported from a foreign land. In this case 

 the outbreak was evidently due to a vicious strain of 

 green-bottles, possessing a harmful character which 

 appeared suddenly and was transmitted through a number 

 of generations as in the case of Nestor. 



Judging from these facts we may expect that any 

 cases of myiasis, occurring in future, will be due to green- 

 bottles and not to other kinds of musc.id flies such as the 

 common Musca, although the latter is ten times more 

 common than the green-bottle and therefore ten times 

 more likely to be the agent of myiasis, if it were not 



