=137. The form of results.= It is almost inevitable that the general adoption of precise methods of measuring the habitat will result in a common form for expressing the physical character of the latter. An actual diagnosis of each habitat is not a difficult matter, after the factors are carefully measured, and will unquestionably lead to very desirable definiteness and precision. The accurate investigation of the physical factors of a number of habitats for one growing season furnishes the necessary material for a diagnosis based upon the mean for the growing season. Similar results for two or three seasons will yield a diagnosis as accurate and as final as that of a formation, or, indeed, as that of many species. The author’s investigations have not yet gone far enough to warrant proposing a final form for this, but the following diagnosis is offered as a suggestion: _Elymus-Muhlenbergia-chalicium._ Habitat: holard 9 per cent, chresard 8 per cent, relative humidity 40 per cent, light 0.6, soil colluvial gravel (gravel 70 per cent, sand 27 per cent, silt 3 per cent), air temperature 65°, surface 82°, soil 59°, wind 10 miles, rainfall 8 inches, altitude 2,800 m., slope 23°, exposure south, surface even, cover open, no active biotic agencies. The detailed comparison of habitats is made most readily by the graphic method of curves, which constitute the most desirable form of expression in connection with the original record upon which they are based. Factor means are particularly desirable for diagnostic purposes, and they furnish valuable curves also. Factor sums are impracticable at present, and it seems doubtful that they will ever be of much value. It is by no means impossible, however, that a more detailed and exact knowledge of the physiology of adaptation, coupled with methods of precision in the habitat, will render them necessary. _Factor Records_