20 



THE SCOTTISH NATURALIST 



same time it does not follow that a comparison of the figures 

 from the different localities obtained in one year would give 

 results which would be repeated in any other year ; in fact, 

 in order to obtain a real basis for comparison, it would be 

 necessary to obtain results for a number of years and then to 

 take an average. Unfortunately I have not the material for 

 making such a comparison, but, without wishing to lay any 

 great stress on them, I have set out in a table a number of 

 results obtained in different localities at different times, and 

 the figures are at least interesting : — 



(To be continued) 



