Experimental Research, Animal Tumors Production of Subcutaneous Sarcomas in Mice with Tars Extracted from Atmospheric Dusts. Leiter, J., Shimkin, M. B., and Shear, M. J. [Nat. Cancer Inst., Bethesda, Md.] J. NAT. CANCER IYST., 3:155-165. 1942. Nine specimens of atmospheric dust were obtained from various locations by three methods of collection. Subcutaneous injection, into male C3H mice, of 20 mgm. of unextracted dust (6 specimens) in saline, or of 0.25 cc. of tricaprylin alone, did not produce sarcomas at the site of injection in 12 months. A single subcutaneous injection of about 50 mgm. of tar, extracted from these dusts by benzene and by ethyl ether and dispersed in tricaprylin, produced sarcomas at the site of injection in 18 of an effective total of 291 mice (strain C3H males and strain A mice of both sexes) in 12 months.inF. L. H. Production of Tumors in Mice with Tars from City Dusts. Leiter, J., and Shear, M. J. [Nat. Cancer Inst., Bethesda, Md.] J. NAT. CANCER INST., 3:167-174. 1942. A new type of dust collector and two others provided specimens of black dust from various cities. Extraction of these dusts with benzene yielded black tars which were then dispersed in tricaprylin and injected subcutaneously into male mice of the C3H strain. A single injection of about 50 mgm. of tar dispersed in 0.25 cc. of tricaprylin was given. The first sarcoma appeared at the site of injection after 5 months. By the end of 16 months the incidence of sarcomas was 8%.--F. L. H. Adenocarcinoma of the Pyloric Stomach and Other Gastric Neoplasms in Mice Induced with Carcinogenic Hydrocarbons. Stewart, H. L., and Lorenz, E. [Nat. Cancer Inst., Bethesda, Md.] J. NAT. CANCER INST., 3:175-189. 1942. The carcinogenic hydrocarbons, 20-methylcholanthrene, 3,4-benzpyrene, and 1,2,5,6-dibenzanthracene, were introduced by specified technics into the wall of the pyloric stomach of mice of both sexes of strains C3H, A, C, C57 black, I, and dilute brown. A t autopsy the following tumors of the stomach were found: involving the glandular portion of the stomach, adenoma, adenocarcinoma, adenoacanthoma, mixed adenocarcinoma and sarcoma, mixed adenoacanthoma and sarcoma, and sarcoma; in the forestomach, squamous papilloma and squamous carcinoma. Adenocarcinoma of the glandular stomach was induced in 6 male strain C3H mice that received 0.8 mgm. of methylcholanthrene dispersed in horse serum and in 2 male strain I mice that received 0.6 mgm. of methylcholanthrene in the same vehicle and in addition 0.14 mgm. of methylcholanthrene in mineral oil. These tumors, which were found at autopsy from 19 to 46 weeks after the time of injection, extended through the muscularis of the stomach wall and infiltrated the peritoneum. Extragastric extension and metastases were not observed. The adenocarcinoma has been successfully transplanted subcutaneously. Extragastric extension and metastases to the liver, pancreas, mesentery, or peritoneum occurred in the case of the other malignant tumors.--F. L. H. Intest inal Adenocarcinoma and In t ra-AbdominaI Hemangio-Endothel ioma in Mice Ingest ing Methylcholanthrene. White, J., and Stewart, H. L. [Nat. Cancer Inst., Bethesda, Md.] J. NAT. CANCER INST., 3:331-347. 1942. Mice of the C3H and C strains were fed rnethylcholanthrene (55 mgm. per 100 gm. of diet) incorporated in the diet for 6 months, after which time they were placed on the basal diet without methylcholanthrene. Each mouse ingested an average of 1 mgm. of methylcholanthrene per day. The mice were autopsied from 42 to 289 days after the beginning of the experiment. Precancerous epithelial lesions and adenocarcinoma occurred in the small intestine; the intestinal carcinomas metastasized to the mesentery, mesenteric lymph nodes, pancreas, liver, and lung. Hemangioendotheliomas involving, singly or in combination, the intestine, mesentery, pancreas, or pancreatic lymph nodes developed and metastasized to the liver and the lung. Pulmonary tumors were induced in both strains of mice, with the higher incidence in the strain C mice.--F. L. H. Action of 5,9,10-TrimethyI-1,2-Benzanthracene on the Skin of the Mouse. Hartwell, J. L., and Stewart, H. L. [Nat. Cancer Inst., Bethesda, Md.l J. NAT. CANCER INST., 3: 277-285. 1942. One hundred and twenty-four mice of the inbred strains dba, C57 black, and I, and of the first generation hybrids derived by reciprocal matings of the dba and C57 black strains, were painted on the skin of the back twice weekly with a 0.06% benzene solution of 5,9,10-trimethyl-l,2benzanthracene. Of these, 102 were suitable for pathologic study. The first papillomas appeared at 39 days in 2 strain I mice. Seventy-nine animals developed malignant tumors as follows: squamous cell carcinoma, 77; fibrosarcoma, 10; mixed carcinogarcoma, 3. Squamous cell carcinomatous metastases to the lymph node or lung occurred in 21 mice. Pigmented foci in the painted area occurred in 61 mice. None of these lesions was considered to be a definite neoplasm. Their morphologic characteristics, nature, and significance are described and discussed.--Authors'