Saline extract from transplanted Ehrlich ascites tumor in mice was fractionated into P₁, P₂, P₃, and P₄. By the same method, X-P₁, X-P₂, X-P₃, X-P₄ were prepared from X-ray irradiated tumor. P₁ and X-P₃ inhibited, and X-P₄ promoted the growth of homologous tumor, and P₃ had an effect of prolonging the life of tumor animals.

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Ehrlich ascites tumor cells were incubated with radioactive donor deoxyribonucleic acid (DNA). The results suggest that the nuclei of the tumor cells can take up both native and heated DNA. Prevailing part of donor DNA seems to be bound with the surface of the host cell nuclei.

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Some effect of serum of rats, partially hepatectomized or fed on 4-dimethylaminoazobenzene (DAB), on the protein metabolism of mammalian cells was compared with that of normal rat serum, using ¹⁴C-glycine uptake by Ehrlich ascites tumor cell protein as an index.
In the serum of partially hepatectomized rats, uptake-promoting factor was liberated shortly after the operation and the serum showed inhibiting effect relatively long after the operation. In the serum of rats kept on DAB-diet, there was an increase of promoting factor within 3 weeks, but on 30th day the promoting effect of serum could not be found.
Because the promoting effect of the serum of DAB-fed rats competed with the inhibit ing effect of the serum of rats long after partial hepatectomy, the promoting factor found in the serum of DAB-fed rats was considered to be the same substance as that found in the serum of rats shortly after the operation.
Effect of serum of partially hepatectomized rats to promote glycine uptake was not lost by dialysis but was lost by deproteinization. Thus, these two factors seem to be of protein nature.

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The anticarcinomatous activity of pretreatment with cortisone and other corticosteroids was tested with transplanted ascites hepatoma, using rats. The indices of this activity were the success or failure of transplantation, the volume of ascites, and the tumor cell and tumor cell island counts therein.
1) Pretreatment with cortisone definitely inhibits the growth of ascites hepatoma, the degree of inhibition being dependent on the dosage.
2) Other corticosteroids tested, Triamcinolone and 4-chlorotestosterone acetate, have no or very slight anticarcinomatous activity.
3) 4-Chlorotestosterone acetate which has an anabolic action interferes with inhibitory action of cortisone, which has a catabolic action.
4) Degeneration of lymph nodes and thymus was induced by cortisone, and the anticarcinomatous efficacy seems to parallel the effect on lymphoid tissues. The degeneration of lymphoid tissues was examined by the size of lymph nodes and thymus, histological change, and the lymphocyte and monocyte counts in the systemic blood.
5) The possible mechanism of the anticarcinomatous activity of pretreatment with cortisone was discussed.

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Experimental tumors were induced in the mouse by a single subcutaneous injection of 0.5% solution of carcinogenic hydrocarbons in acetone; 9, 10-dimethyl-1, 2-benz-anthracene, 3, 4-benzopyrene, 5, 6-dibenzanthracene, and 20-methylcholanthrene. However, histological difference of the tumors depending on the kind of hydrocarbons was hardly observed in the present work.
Histochemical observations were made on these tumors as to the distribution and localization of each enzyme. Succinic dehydrogenase, acid phosphatase, β-esterase, aminopeptidase, and β-glucuronidase react weakly or moderately in the parenchymal cells of tumors, but alkaline phosphatase is absent in various typed cells of tumors. In giant cells, succinic dehydrogenase, β-esterase, and β-glucuroninase were intense in activity, but other enzymes were absent. Acid phosphatase, β-esterase, and β-glucuronidase were demonstrated in cells lining the cyst wall.
The present experiments did not reveal that experimental sarcoma diplays a special enzymatic pattern in histochemical observations.

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Comparative studies were carried out on the possible parallelism between the effect of various anticancer agents and the restoration of the lowered activities of liver catalase and uricase to normal in mice bearing Ehrlich ascites carcinoma. Changes in liver xanthine oxidase activity during the therapy were also measured.
1) The alkylating agents used, which were active against Ehrlich ascites carcinoma, restored the lowered activities of catalase and uricase in tumor-bearing mice in parallel with their effect on the prolongation of the life span. However, they had no influence on the activity of these enzymes in normal mice.
2) Sarkomycin had the same effect as these alkylating agents.
3) Among the purine antagonists tested, 6-mercaptopurine and 8-azaguanine, which had considerable anticancer activity against Ehrlich ascites carcinoma, caused further reduction in the activities of catalase and uricase in tumor-bearers, and the restoration of these enzyme activities to normal was delayed. The non-effective purine antagonist, 2, 6-diaminopurine, had a tendency to depress the lowered enzyme activity in tumorbearers. All the purine antagonists tested inhibited xanthine oxidase activity in both normal and tumor-bearing mice.
4) Folic acid antagonists, which were not effective against Ehrlich ascites carcinoma at the dose level tested, further depressed the activities of catalase and uricase in tumor-bearing mice and subsequently did not restore the enzyme activity to normal. In normal mice, only catalase activity was inhibited, while xanthine oxidase activity was almost unaffected in both normal and tumor-bearing mice.
On the basis of these results, it is concluded that the effects of the anticancer agents tested in increasing the survival rate and in restoring the lowered activities of liver catalase and uricase in tumor-bearing mice were not always in parallel.

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DNA synthesis in polyoma virus-infected mouse embryo cultures was studied by means of autoradiography and correlated cytological and immunofluorescent analyses. In confirmation of previous reports concerning the "transformation" of infected cultures, continuously-growing cell populations were obtained. Nevertheless, these cell populations were found to be merely "polyoma virus carriers, " capable of producing parotid tumors after inoculation into newborn mice, but not transplantable as neoplastic cells.
The autoradiographic results obtained indicated that de novo synthesis of viral DNA takes place. Increased DNA synthesis in polyoma virus infection was concluded to be a primary response caused by active synthesis of viral DNA. In addition, it was evident that synthesis of host-cell DNA also continued to a certain extent.

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Based on experimental studies, administration of anticancer agents before, during, or after a surgical operation was found to prevent metastatic recurrence of tumor to some extent. Clinical application of anticancer agents in surgical operation is described in detail.

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There exists a large amount of catalase in pellet fraction which cannot be estimated in the usual homogenation (12 strokes) and treatment of the homogenate with deoxycholate releases catalase from pellet. By using the method of determination of catalase activity described in this paper, the catalase in pellet can be determined and individual deviations of catalase values are minimized. It is also shown that the difference of the degree of homogenization has negligible effect on the determination of liver catalase activity after adding deoxycholate so that one can always obtain constant values even when using different homogenizers. Moreover, the toxohormone activity can be estimated exactly when the homogenate is treated with deoxycholate.

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The method of gel precipitation of Ouchterlony was used for a comparative study of water-soluble antigens of normal and tumor tissues from the same cancer patient.
After absorption with normal tissue antigens, antiserum against tumor tissue showed significant precipitation bands in reaction to the same tumor antigen.
Likewise, antiserum against normal tissue precipitated normal tissue antigens after absorption with tumor antigens. It is evident, therefore, that human cancer tissue and normal tissue of the same patient, from which the former has arisen, possess distinctive antigenic components.
Limitation of this method as a detective tool for tumor-specific antigen was also discussed.

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Intrahepatic topographical distribution of the protein-bound dye was investigated by autoradiography, using ¹⁴C-labeled 4-dimethylaminoazobenzene, in a precancerous liver of a rat which was induced by preliminary feeding of cold Butter Yellow. In the hepatic parenchyma, the highest number of ¹⁴C grains was observed in a region of benign nodular hyperplasia and a lesser number was found in atypical hyperplastic loci. The grains were almost negligible in both cholangiofibrosis and cystic region.
The significance of these findings and comparison with Weiler's findings or with results of our previous experiments are briefly discussed.

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The changes of π-electron distribution in atoms in purine bases participating in the hydrogen-bond formation in Watson-Crick model of deoxyribonucleic acid are calculated by the simple linear combination of atomic orbital-molecular orbital (LC-AO-MO) method assuming that the alkylating agents attack the guanine at its 7-N position and adenine at its 7-N and 3-N positions. The changes in electron density are believed to make an alteration of the hydrogen bond with respect to the mode of pairing. It is assumed that the tautomeric change of guanine-cytosine pair results and weakens the hydrogen bond strength of adenine-thymine pair. These changes are discussed in relation to the biological effect of alkylating agents such as mutagenic, carcinogenic, and carcinostatic activities.

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A growth-promoting substance(s) was isolated from crude chick embryo extracts by precipitation with 30-70%(v/v) ethanol. It is non-dialyzable and nucleoprotein-free. It differs from oncotrephin in certain respects. Both heating at 100° for 30 minutes and trypsin digestion abolish its effect.

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The amino acid composition of hyaluronic acid-protein complex isolated from Rous sarcoma and synovial fluid has been determined by ion-exchange chromatography. There were no significant differences in amino acid composition of the complexes between these two sources, except for valine, tyrosine, and phenylalanine. Absence of hydroxyproline, ascertained by specific chemical reaction, indicates that the complex is not made of a collagen-like protein. To some extent, composition of the protein of this complex is closely similar to that of serum fractions, and mainly of γ-globulin.

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