26 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. LXi. 



ments with the same soil, found in one gramme of 

 earth — 



perhaps it will be asked how it is possible to make such 

 exact calculations. A survey of the methods will show 

 the problem not to be as difficult as it seems. If the 

 earth sample be taken from the upper layer of the soil, we 

 do it directly with a sterilised spoon, and then place the 

 sample in a sterilised tube plugged with cotton wool. If 

 the sample falls to be taken from the deeper layers, the 

 above-mentioned method will not suffice, as in digging, 

 the earth of the deeper layers will become mixed with 

 parts from the upper layers, which will tumble in. To 

 obtain an accurate sample from a layer of any depth, 

 Frankel's borer is employed. The boring body of this 

 instrument is about Ih inch in diameter. An inch or two 

 above the boring point is an opening between 4 and 

 5 inches long and about 1 inch deep. This opening is 

 destined for the earth sample. The borer, with a handle 

 which can be lengthened out to 5 feet, is pressed into the soil, 

 and the mechanism is so arranged that as long as the borer 

 be twisted from right to left the opening mentioned above as 

 in the side remains closed. When the desired depth has 

 been reached, Ijy turning the borer in the opposite direction 

 the covering to the opening is pushed back and the opening 

 exposed ; the earth falls in, the opening is again closed, and 

 the sample pulled up. One gramme of this earth is care- 

 fully weiglied out and placed in a quart of water, which 

 has been sterilised by boiling, the mixture being thoroughly 

 shaken. Meanwhile one has ready a glass tube containing 

 the gelatine nourishing material for the bacteria. The 

 gelatine has been rendered germ free by repeated heating 

 in a steam bath. This gelatine, when liquefied by a gentle 

 warming, has added to it carefully by means of a sterilised 

 pipette 1 ccm. of the above mixture of water and earth. 

 After a thorough mixing, the entire contents are poured 



