444 The Manure Heap and the TIoiixe-Flji 



I have before nie a list of over lOU autliois of voliinies ami papers 

 dealing with the subject. With so formidable an array of literature 

 available it may be asked what further point remains to be elucidated. 

 All are agreed that house-flies breed in almost any refuse and particularly 

 in manure. So certain and universally accepted is this fact that it has 

 induced an almost equally general converse beUef that all iiuniure breeds 

 liouse-flies. 



The object of my research has been to ascertain to what extent this 

 latter hypothesis could be supported by actual experiment. 1 am 

 indebted to Dr E. J. Russell, the Director of the liothamsted Experi- 

 mental Station, for providing every facility for carrying out the work 

 under the most favourable conditions, and to the Board of Agriculture 

 for a grant towards the personal and material expenses incurred. 



I should like to take this opportunity of thanking all the members 

 of the Staff of the Rothamsted Laboratory for their many kindnesses, 

 and especially would I express my gratitude to my friend 

 Mr E. H. Richards, who not only assisted me in much of the practical 

 work of erecting the apparatus but also attended to the experiments 

 during a short period when I was incapacitated owing to a slight accident. 



I am also greatly indebted to my friends Mr J. E. Collin and 

 Mr A. H. Hamm for assistance in naming some of the flies observed 

 in the course of the experiments. 



The farm manure heap may be purely stable manure or it may be 

 mixed refuse containing the excreta of other animals in addition to 

 horses. Stable manure is usually stored light, i.e. it is not trodden 

 down and compacted, whilst mixed manure ma}' be stored either light 

 or compacted. Such heaps may be out in the open at a considerable 

 distance from dwellings, or they may be quite near to a house or houses. 

 Neither of these conditions resembles the state of affairs which obtains 

 when a stable manure heap occurs in a confined space in a town, and is 

 closely adjacent to many houses and shops, with kitchens, bakeries, 

 etc., in the immediate neighbourhood. 



To reproduce the two former conditions suggested above, together 

 with the different nature and treatment of the manure, six experimental 

 heaps were established. Three of these were placed on land adjoining 

 the laboratory, and their relation to their surroundings may be gathered 

 from the accompanying sketch (Fig. 1). The experimental heaps 

 are there marked 1 , 2, and 3. They were established on ground forming 

 part of an area which is used by the laboratory for out-door experiments. 

 The nearest dwellings are the cottages shown at a distance of some 



