Samples of bracken were taken at fortnightly intervals from June to November at two centres. These were separated into leaf and stem and analysed.

Larger samples were treated for the preparation of proteins and sugars by passing the bracken through a roller-mill, precipitating the protein with acid and concentrating the juice for sugars.

Chemical composition. The main points in the analyses of the whole plants were as follows, all figures quoted being on a dry-matter basis:

(1) The crude and true protein contents of young bracken in early June were high, 21 and 18%, but these fell rapidly to 10% in mid-July and finally to 3% in October.

(2) The lignin content was high throughout, rising from almost 20% in young bracken to 34% in the nearly dead material.

(3) The cellulose content followed the lignin content.

(4) In July and August the bracken contained about 10% of total sugars. A rapid fall occurred in October, and the final samples contained very little sugars.