A consideration of the clinical course of scurvy sheds but little light on this aspect, and can be interpreted as well for as against the action of a toxin. The nervous system, which is well known to be particularly vulnerable to toxins, is but slightly affected--the cardiorespiratory phenomena (indicating an involvement of the pneumogastric nerves), the occasional changes in the optic disks, and the abnormality of the tendon reflexes constitute the aggregate. In a general way it may be stated that the symptoms resemble those brought about by poisons of various kinds--the cottonseed poisoning in swine, the toxic products of the wheat embryo, or even mercurial poisoning in man.[6] The nervous symptoms, especially the irritability of the heart, remind one of the enterogenous intoxication or enterotoxic polyneuritis described by Von Noorden. Such analogies are interesting and suggestive, but can be accorded little weight in deciding the question at issue. [6] In chronic mercurial poisoning the following suggestive symptoms occur: anemia, bleeding and spongy gums, loosening of the teeth, a quickened pulse, ulcers of the extremities. At times mercury attacks the nervous system, producing palsy. The resemblance is heightened by the fact that calcium metastases have been found in the muscle in experimental scurvy (Hart and Lessing) comparable to those characteristic of mercurial poisoning. If a toxin is to be regarded as the proximate cause of infantile scurvy, the question naturally arises as to the nature of the toxin. Is it exogenous or endogenous? There is sound basis for believing that the hypothetical poison is not introduced preformed in the food. In the first place, infantile scurvy frequently develops in babies who receive milk of the very best grade indeed, in contradistinction to rickets, this is not preëminently a disease of the poor. Furthermore, there is no relation between the concentration of the food mixture and its liability to induce scurvy. For example, if among a large number of infants receiving pasteurized milk from a common source, some are given the milk diluted by one-half, others given it diluted by one-third, and still others whole milk, the last group will show the least tendency to scurvy, which we should not expect were the poison contained in the food. Nor is it at all uncommon to encounter scurvy in an infant which has been fed with a very dilute milk mixture. Another side of this question should, however, be mentioned--stale pasteurized milk is more apt to produce scurvy than the freshly pasteurized, but here again the injury is in inverse ratio rather than in direct ratio to the amount consumed. There are reports of adult scurvy having been occasioned by decomposed food, such as Torup's investigation of Nansen's polar expedition, but the diet had not been faultless in other respects. The experiments of Jackson and Harley, who produced scurvy in monkeys by