AERATION OF THE SOIL BY EARTHWORMS 397 



have evaporated into it from the potash in E. G served to 

 prevent any moisture from the aspirator from striking back 

 into the apparatus and affecting the results. Sometimes B was 

 covered with a box so that the worms were kept in complete 

 darkness. 



The results obtained are given in the following table ; the 

 last column of figures in the table is obtained by dividing the 

 weight of carbon dioxide exhaled in twenty-four hours by the 

 weight of the worms tested. For convenience we shall call this 

 the carbon dioxide factor. 



Carbon Dioxide breathed out by Worms 



From the above results a number of very interesting facts 

 may be gleaned. These may be summarised as follows : 



1. The amount of carbon dioxide exhaled is not proportional 

 to the body weight of the worms, the smaller species exhaling 

 larger quantities of the gas than the larger in proportion to 



1 This result is probably a little low. The worms were dying towards the end 

 of the experiment. 



