LIFE HISTORY 35 



Summary of Duration of Life Round 



In summarizing the duration of the life round, we 

 find that the writer's Washington observations made 

 the total life round approximately ten days, as indi- 

 cated in an earlier paragraph. These were midsummer 

 observations made in August, 1895, on the Depart- 

 ment of Agriculture grounds in the city of Washing- 

 ton, but in a warmer climate they may be hastened 

 even beyond this minimum. Thus, in India Surgeon 

 Major F. Smith, of the Royal Army Medical Corps, 

 found at Benares that from a collection of one day's 

 fresh droppings of three horses the adult Musca domes- 

 tica was obtained on the eighth day after the laying of 

 the eggs, thus shortening the period considerably. 

 Moreover, Doctor Hewitt's minimum rate of growth 

 was : tgg, eight hours ; first-stage larva, twenty hours ; 

 second-stage larva, twenty-four hours; third-stage 

 larva, three days; pupa, three days — a total of eight 

 days and four hours, surely a much shorter period 

 than often happens in England, although the occa- 

 sionally high summer tem.perature combined with the 

 moist climate of that country may occasionally bring 

 about this shortening. Mr. Newstead's observations 

 in Liverpool, on the other hand, show a minimum 

 period of from ten to fourteen days and a maximum 

 of from four to five weeks or longer. 



Dr. A. GrifBth, Medical OfTlicer of Hove, England 

 (a seaport on the English Channel), experimented with 

 house flies during 1904-7. He gives as the minimum 



