Urquhart. — On the Habits of Earth-Worms in Neio Zealand. 269 



parts of Britain. This is to be attributed to there being — the conditions 

 being equal — a far greater number of worms in an acre of ground in this 

 country. 



Darwin says that the number of worms in old pastures is unknown, but 

 assumes that there may be 26,886 per acre. According to Henson there 

 are 53,767 worms in an acre of garden ground, and about half that number 

 in cornfields ; possibly this estimate may be found too low for many parts of 

 Britain. My own estimate of the number of earth-worms (348,480) living 

 in an acre of pasture land, in the vicinity of Auckland — which appeared in 

 an early number of the " N.Z. Journal of Science " — although a low average 

 was given, was so high compared with Henson's, that I went through the 

 work of counting the worms over again this winter ; the plan adopted was 

 to take a straight course across several parts of a field, taking out a square 

 foot of soil every twenty paces. The worms have evidently increased 

 since my former observations, so that the results were still more striking. 

 My accurate friend Mr. T. F. Cheeseman, F.L.S., thinking it possible that 

 I might be unconsciously influenced in selecting a spot for examination, 

 suggested the work should be systematically done with the aid of a tape. 

 Accordingly fresh lines were run between some of the former ones, in a 

 portion of a field 17 years in grass. A piece of fair average ground was laid 

 out in squares of 120 feet, a square foot of soil was then taken out at each 

 corner. As the accuracy of my former observations was being put to the 

 test, and at the time (September) most of the worms were in the turf, 

 instead of carrying out my research merely with the aid of a spade, I picked 

 every particle of turf with my fingers; over three hours work gave the 

 following results : — 



Number of Earth-worms in each square foot of soil. 



6. 3. 10. 27. 56. 19. 5. 10. 0. 12. 12. 20. 25. 17. 9. 11. 36. 17. 



12. 3. 20. 14. 48. 22. 24. 27. 40. 14. 12. 10. 15. 18. 18. 26. 13. 19. 



Worms hanging to the side-walls were not counted, and the blank hole — 



only the second in that field — was surrounded with worms. 



These figures give an average of 18 worms per square foot, or 784,080 

 per acre. Although this average is rather striking compared with Henson's, 

 the difference in the actual weight of the worms is not so marked. Von 

 Henson's standard weight of a single worm is 3 grams, accordingly the 

 53,767 worms would weigh 356 pounds. The greater proportion of the 

 worms met with in our fields are the common L. campestris ; the larger 

 forms of this species weigh 12 grains — 50 averaged 6 J grains ; allowing for 

 the few intermixed lighter species, the average of the entire number of 

 worms may be taken at 6 grains, this would give a weight of 612 lbs. 9 ozs. 

 As my former tests in other parts of the farm, where the conditions were 



