APPENDIX. Bracken is known to contain considerable amounts of carbohydrates and is available in this country in considerable quantities. Hence use of it does not involve shipping. In spite of the obvious appeal of the suggestion to manufacture food yeast from the carbohydrates contained in bracken, I, regretfully, cannot support this suggestion at present for the following reasons: (1) Although it is known that food yeast can be made from hydrolysed bracken, i.e. bracken boiled with dilute acid, no feeding tests, either on animals or on human beings have been carried out on food yeast so prepared.