BY J. J. FLETCHER, M.A., B.SC. 527 



a good idea of the abundance of these worms. On one occasion 

 when the length of the furrows was about 80 yards I walked 

 behind the plough and counted all the worms I could see either in 

 the furrows or sticking out of the overturned clods, and I found 

 that for a number of furrows the average number of worms visible 

 under these circumstances was about 50 per furrow. Allowing a 

 foot for the width of soil turned over for each fresh furrow, these 

 would give nearly 10,000 worms to the acre. This is a small 

 estimate compared with that given by Hensen for European 

 worms, namely 53,767 per acre (1), and quite insignificant 

 compared with two given by Urquharb for New Zealand worms, 

 namely 348,840 and 784,080 per acre (2). But while Hensen's 

 estimate is for worms found in gardens, in which situations he 

 believes they are twice as numerous as in cornfields, and Urquhart's 

 are for worms living in pasture land, which in one case had 

 been 17 years in grass, my estimate is for worms in virgin soil, 

 for the land to which I refer was not cleared during my earlier 

 visits, and it was being ploughed for the first time on the occasion 

 to which I refer. Moreover, my estimate is obviously below the 

 mark for several reasons. In the first place the plough did not 

 turn up the soil to a depth exceeding six inches if so great, 

 and there were probably some worms below this level ; and 

 secondly if the clods had been broken up and carefully examined 

 more worms would have been found. Hensen takes one gram 

 (15*4 grains) as his standard of weight of a single worm, and 

 Urquhart gives 6 grains as the average weight of his specimens, 

 but that of the Burrawang worms would, I think, exceed the first 

 of these weights, the largest worms, which however are least 

 numerous, of which I have one specimen measuring 30 inches 

 and a still larger one measuring 42 inches, probably weighing 

 over 4oz. Allowing therefore for the large size of the worms and 

 for the requirements of additional space on this account, it may 



(!) Quoted by Darwin, loc. cit. p. 159. 



(2) "On the Habits of Earthworms in N.Z." Trans, and Proc. of the 

 N.Z. Inst. Vol. xvi, 1883, p. 269. 

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