The attack on the McCollum view continued from various quarters. Chick and Hume in England examined his grain and milk fed series and showed that those receiving much milk and little grain recovered while those on the reverse diet died. They held that all guinea pigs with scurvy become constipated regardless of the diet. They gave large quantities of dried vegetables well cooked in water, in order to provide bulk, but this did not prevent scurvy and neither did the use of mineral oil. Hess found that in infants with scurvy there is a history of constipation but that while potatoes which are not laxative cure scurvy, malt soups which are laxative permit its development. He found that scurvy in infants is relieved by amounts of orange juice entirely too small to have a marked laxative action and was unable to secure cures with McCollum's artificial orange juice. The most convincing argument was the discovery that orange juice administered intravenously still exerted a curative action which could not in any way be laid to its effect on constipation. To these attacks McCollum's co-worker, Pitz, suggested a new hypothesis. It was well known that in rats and man the intestinal flora can be changed from a putrefactive form to a non-putrefactive type by feeding milk sugar or lactose. If this were true, as was admitted by all, and the scurvy due to the absorption of putrefactive products, this absorption might still be the causal factor whether constipation was present or absent. To determine this point he fed his guinea pigs on oatmeal to which he added a carbohydrate diet. When the carbohydrate was lactose he was able to cure and prevent scurvy. This evidence was not considered convincing, however, since in his experiments milk was given freely. Furthermore, Cohen and Mendel demonstrated that in their experiments pure lactose neither prevented nor cured scurvy while Harden and Zilva could find no antiscorbutic value in either cane sugar, fructose, or sirup. These authors believed and stated that Pitz's results were entirely attributable to the free use of raw milk.