The relation of _loss of weight_ to the development of the scurvy requires consideration. In experiments carried out on rats to test the diets in respect to the water-soluble and the fat-soluble vitamines, the weight curve is used as the main criterion to judge whether the foodstuff is adequate. In guinea-pigs we cannot employ the weight curve as a criterion. Not infrequently an animal develops scurvy, and nevertheless does not lose in weight, but even gains slowly and steadily. This occurs when the appetite remains good, and the dietary is complete except for antiscorbutic vitamine. The same holds true for human scurvy, as we have noted in connection with the symptomatology. We have attempted to make up for this defect by adding to the charts a curve representing the clinical course (Fig. 10). Although this curve is computed on an empirical basis, it gives a comparatively true picture of the disease and is far more exact than attempting to portray the disease by means of a weight curve.[38] Indeed, when we rely on the latter method it is impossible frequently to illustrate graphically the reaction of guinea-pigs to various influences. Another disadvantage of the weight curve is that it is influenced by factors having no direct relation to scurvy, especially infections of various types which retard the gain. [38] A maximum count of 35 was formulated, representing the highest degree of clinical scurvy. This includes three grades of beading of the ribs, four of tenderness of each knee and wrist joint, and four of swelling of each of these joints. It is apparent from the clinical curve (Fig. 10) that an animal may have developed a marked degree of scurvy (20 points), and gained rather than have lost in weight. [Illustration: FIG. 10.--Hay, oats, and water _ad libitum_ during period I resulted in a lack of gain in weight, and in a development of scurvy. During period II, 1.5 c.c. of orange juice were given daily, and as will be seen there was a marked gain in weight and disappearance of the scorbutic signs, although, as is generally the case, they continue to develop for a short while after an antiscorbutic is given. When the orange juice was discontinued in the third period, the weight once more fell and the scurvy redeveloped. The broken line represents the course of the scurvy, and is a composite formed on the basis of the aggregate of the scorbutic signs. Each square represents a 2-day interval.]