1. A mixture of anhydrous lanolin with about equal parts of olive oil was the most efficacious ointment tested for protecting our animals from mineral-oil dermatitis and cancer.

2. Some commercial products consisting of mixtures of the alcohols and esters contained in lanolin were, on the whole, less efficacious: possibly the apparent benefit was mostly due to the olive oil with which they were diluted.

3. Olive oil, glycerine, commercial soaps, etc., gave varying degrees of protection, the last being particularly useful under some circumstances.

4. In experiments with gas tars, lanolin does not appear to afford protection when relatively small quantities of it are mixed with the tar or when relatively large doses of tar are applied to the animal, before or after lanolin treatment.

5. Where the experimental conditions appear to conform more to those prevailing among most tar workers, lanolin has a definite protective action.

6. Separate application of the carcinogenic agent and the prophylactic agent as a rule results in a lower yield of tumours than applications of an admixture of the two. In this respect it is to be noted that, where the animals were treated with lanolin separately, the quantity applied was several times greater than that of the tar itself (similarly in mineral oil experiments). This, of course, was not the case in our experiments with the lanolin blends.

7. Relatively more lanolin is required to protect against gas-tar dermatitis and cancer than is required to protect against toxic oils or synthetic tars. This is probably due to the presence in gas tars of special inhibitory substances. Note the analogy in the action of small quantities of acid on mineral oils, the potency being raised, whereas larger quantities may lower it.