Hubert M. Morris 283 



the mechanical and chemical analyses; and for help in the identification 

 of species of Insecta, Myriapoda and Arachnida to Messrs S. G. Brade- 

 Birks, J. M. Brown, E. A. Butler, H. St J. K. Donisthorpe, F. W. 

 Edwards, H. F. Fryer, J. E. Hull, R. C. L. Perkins. 



1. Description of the Area examined. 



The area dealt with in this investigation was the Broadbalk field 

 belonging to the Rothamsted Experimental Station, Harpenden. The 

 soil of the Rothamsted fields is "clay with flints," which overlies chalk. 



Broadbalk field is roughly rectangular in shape, the long sides running 

 W.N.W. to E.S.E., and it lies on a gentle slope, the south-east side being 

 the lowest, this side being slightly over 400 feet above sea level. 



The field is divided into a number of plots, of which numbers 2 and 3 

 were dealt with in this investigation. Plot 2 has received annually a 

 dressing of farmyard manure at the rate of fourteen tons to the acre 

 since 1843. Plot 3, which is a control, has received no farmyard or 

 artificial manure of any kind since the commencement of the experi- 

 ments in 1843 and actually since 1839. 



These plots are about half an acre in area, and lie side by side along 

 the northern side of the field, being separated by a path two yards wide. 



The effect of the different treatment of the plots is very noticeable 

 in their yield of grain and straw, and in the general growth of the wheat 

 and weeds. This treatment having been the same in either case for so 

 many years makes them particularly well fitted for an investigation of 

 the soil fauna which they support. 



The plots were ploughed on October 13th, the manure having been 

 applied to plot 2 just previously. 



2. Method of Investigation. 



The samples of soil which were examined in the course of this in- 

 vestigation were taken from the western end of the plots, and were taken 

 from the edges of the plots so as to disturb the soil of the plots as little 

 as possible. Successive samples from the same plot were not taken next 

 to each other, nor were any two samples taken nearer together than 

 about a yard. 



The method of taking the sample was as follows. Four iron plates 

 were used, two of them twelve inches long by ten inches wide, one twelve 

 inches long by nine inches wide, and one four inches long by nine inches 

 wide. Each plate had an iron bar fastened to it at the top, and each of 

 the three larger plates had two projecting teeth at the bottom. These 



