although their cæcums were impacted with fæces of a putty-like consistence. Guinea-pigs do not seem to be able to tolerate a diet containing a large quantity of the fat of cow's milk. Such a diet leads to impaction of the large intestine resulting in death, but does not induce scurvy. Jackson and Moore produced a condition of this kind by feeding pigs with cream containing 26 to 28 per cent. fat. "In every case," they write, "the large intestine was distended with light mustard-colored semi-solid fæces." This pathological condition is not understood, but is quite distinct from scurvy, and remarkable in view of the fact that the milk of the guinea-pig contains as high as 25 per cent. of fat. It is an interesting illustration of the marked biological difference in the butter-fat of various species. [Illustration: FIG. 8.--Shows a period with the development of scurvy, and one where it was cured by giving orange juice. It will be noted that there was no marked constipation while the animal had scurvy. During a period of a few days the amount of stool was scanty, corresponding to the decreased intake of oats and hay on the days preceding. Broken line represents clinical course of scurvy.] Nor was it found, as McCollum and Pitz claimed, that antiscorbutics were replaceable by laxatives in the diet. Without entering into the details of this aspect of the subject, which will be considered in the chapter on symptomatology, it may be stated that attempts to prevent the occurrence of scurvy or to cure it by means of laxatives invariably failed. Chick, Hume and Skelton, as well as Hess and Unger, gave oleum petrolatum to a series of pigs without the slightest favorable effect. Hart, Steenbock and Smith recently reported that they had administered 1 c.c. of this oil on alternate days to one series of pigs, and 2 mg. of phenolphthalein on alternate days to another series, without relieving the scurvy. Cohen and Mendel, in order to test the adequacy of their diet as to roughage, supplemented it with additions of considerable filter paper and sawdust, "without averting the appearance of scurvy." It is evident, therefore, that constipation does not play an essential rôle in the pathogenesis of scurvy in the guinea-pig, and that antiscorbutics are by no means synonymous or interchangeable with laxatives. These results accord with observations on infantile scurvy.