The structural features and growth of the ascites hepatoma of the rat were observed throughout the whole life span of the tumor-bearing animals. The structural unit of the ascites hepatoma is a hepatoma island consisting of two cellular elements, cancerous hepatic cells and endothelial cells, which are in a symbiotic association. The hepatoma cells of the ascites hepatoma show their regular mitotic activity in the presence of the endothelial cells. Suggestion was made that the hepatoma island can accomplish its characteristic growth and function under the symbiotic association of the hepatoma cells and endothelial cells.

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The present paper describes the results of the karyological study of the tumor cells of the Takeda sarcoma in rats. It was found that there is present a strain (or strains) of tumor cells hoving a subtetraploid complex of chromosomes, and remaining unaltered in chromosome individuality through succesive transplant generations. The growth of the tumor is due primarily to the proliferation of these strain cells. The chromosome complex of the strain-cell consists of two distinct groups, namely a group of rod-shaped chromosomes and a group of V-, and J-shaped ones of varying sizes. Among the two-armed chromosomes, a large J-shaped chromosome, tripartite in structure, and a large V-shaped element, one or rarely two in number, are very prominent due to their outstanding size.

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Morphological and genetical studies have been made on a tumorous growth found in the wild strain of Drosophila virilis which were collected in the suburbs of Sapporo City, Hokkaido. The tumors are benign and melanotic; they take various sizes and shapes. They appear mainly on the mesonotum, scutellum, pleula and head regions. The tumors appear as pigmented bodies in the imagos within ten to twenty days after emergence. The results of crossing performed between the tumorous strain and the wild strain seem to suggest the occurrence of a maternal influence on the incidence of tumor in the offspring.

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[in Japanese]

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An attempt was made in this paper to investigate the activities of catalase and uricase of liver of rats in the course of liver cancer production by AAF feeding. The drastic decrease in the activity of catalase and uricase was recognized in the liver cancer. And the considerable reduction in the activity of both enzymes was seen when the liver showed marked hyperplasia or cirrhosis. However, no remarkable change was occured at the early stage of liver changes in the enzymatic activities. Both catalase and uricase contain iron in the molecules. These experimental data in the activities of enzymes, catalase and uricase, of rats fed AAF have the same tendency to that of rats in the DAB carcinogenesis.

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The present study is an attempt to ascertain the relative activity of phosphatase and esterase of serum and liver of rats fed on 2-acetylaminofluorene (AAF) during the course of the production of liver cancer, comparing with that of rats fed on p-dimethylaminoazobenzene (DAB).

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The asparaginase activities of several tissues of rats fed with carcinogens, p-dimethylaminoazobenzene (DAB) and 2-acetylaminofluorene (AAF), were studied.
The activity of liver asparaginase was very low after the long period of carcinogen feeding. When the carcinogenic diet was discontinued after a prolonged feeding, the activity of liver asparaginase recovered, tending to the value of normal rat liver, notwithstanding the liver lesions, except hepatoma.
The activity of hepatoma tissue was always extremely low whether it has been induced by DAB or AAF and under any feeding condition.
In the short period of AAF feeding the liver activity was diminished weekly and reached to the lowest within 3-4 weeks. The result is quite similar to what has been publicated elsewhere about the DAB fed rats.
The asparaginase activity of tissues other than the liver, such as kidney, brain, testis of DAB fed rats were studied. No remarkable difference was found compared to normal corresponding tissues. The activity of kidney and brain asparaginase of AAF fed rats also showed similar results.

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Activities of desaminases for ribosenucleic acid and desoxyribosenucleic acid of the hepatic tissues of rats during p-dimethylaminoazobenzene carcinogenesis were investigated.
pH-Activity curves of these enzymes had two pH optima on acid and alkaline sides, where the activity level could be easily distinguished from each other.
These enzymes contained in pathological livers had always higher activity than those of control livers and were markedly notable in the case of hepatoma, especially at alkaline side optimum.

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1) The enzymatic hydrolysis of homologous bromo- and chloro- fatty acid amides in the liver of rats fed on hepatic carcinogen, p-dimethylaminoazobenzene or 2-acetylaminofluorene, has been investigated.
2) Aqueous homogenate of normal liver had the marked activity to evolve ammonia from the obove mentioned substrates. Its optimum pH was situated in the range of pH 8 to 9.
3) The phathological but non-cancerous liver showed fairly good activity, when the rats have been removed from their carcinogenic diet and were placed on normal diet for many weeks.
4) Usually the activity fell keeping step with the development of liver lesions and in case of hepatoma nodulus the activity was extremely low.
5) The pathological but non-cancerous liver of rats fed on p-dimethylaminoazobenzene continuously showed low activity.
6) The substrates tested seem to have some characteristics. Aliphatic compounds of straight-chained and rich in carbon atoms were decomposed easier by liver extract than iso and lower fatty acid derivatives.

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Experiments were described demonstrating that tumor extract contains a dialyzable substance which, when injected into normal mice, markedly depresses the liver catalase activity, and that enzymic digestion of the non-dialyzable toxohormone concentrate readily produces the dialyzable substance with similar activity.
Possibility was suggested that the dialyzable factor may represent the elementary form of toxohormone, which may occur in cancer tissue mostly as aggregates of such forms or as conjugates with some other substance.

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[in Japanese]

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