"Spawn is obtained the most readily and in abundance in parcels of decayed dung and dungy composts; but commonly more plenteously and good in rotten horse stable dung, composed of the short dung and moist litter together, as cleared from the stables, either collected in dung-heaps or formed into hot-beds, composts, &c. when it has remained some months till its fermentation and heat are decreased, and a state of decay and putrefaction brought on. This kind of dung being more adapted to the generation of spawn than any other, is a favourable circumstance, as horse dung is to be every where met with."