An attempt was made to justify these conclusions experimentally, but unfortunately, owing to unavoidable circumstances, the number of fish which could eventually be spared was very small, so that not more than some three or four individuals could be fed on any one specialized diet. Such results as were obtained,
however, supported the view above expressed. It may be noted further that the carp and the gudgeon both seek their food from the bottom. The present account deals simply with the comparative anatomy and histology of the mouth, pharynx, and gut of the three types. This will be followed by an account of the cytological, lustochemical, and physiological aspects of the problem so that the 'functional morphology' and the adaptive correlations may thereby acquire a firmer basis.