162 WEIGHT OF EAETH Chap. III. 



founded on the numbers found in a garden, 

 and Hensen believes that worms are here 

 twice as numerous as in corn-fields. The 

 above result, astonishing though it be, seems 

 to me credible, judging from the number of 

 worms which I have sometimes seen, and 

 from the number daily destroyed by birds 

 without the species being exterminated. 

 Some barrels of bad ale were left on Mr. 

 Miller's land,* in the hope of making vinegar, 

 but the vinegar proved bad, and the barrels 

 were upset. It should be premised that acetic 

 acid is so deadly a poison to worms that 

 Perrier found that a glass rod dipped into 

 this acid and then into a considerable body of 

 water in which worms were immersed, in- 

 variably killed them quickly. On the morn- 

 ing after the barrels had been upset, " the 

 " heaps of worms which lay dead on the 

 " ground were so amazing, that if Mr. Miller 

 " had not seen them, he could not have 

 44 thought it possible for such numbers to 

 " have existed in the space." As further evi- 

 dence of the large number of worms which 

 live in the ground, Hensen states that he 



* See Mr. Dancer's paper in ' Proc. Phil. Soc. of Manchester,' 

 1877, p. 248. 



