This paper describes two types of mini - tomographic apparatus recently manufactured by the authors for the purpose of introducing them in the laboratories of anatomy, pathology, etc. Hithertofore, the tomographic apparatus had not been in use by these laboratories of basic medical sciences because of its physical size and expensive cost of maintenance.
Therefore, our mini - tomographic apparatus, made of wood or other material which is easily penetrable by X-ray, is small and light enough, so that anyone can operate them on his laboratory desk to aid him in his research routine.
These tomographic apparatus are of two types : parallel incline type and revolving type. After our pilot manufacture of these devices, they were put to tests in the following manner in order to evaluate their practicability.
1. Parallel incline movement type.
When a material is put to test in the passage of X-ray with a film directly beneath the material, both the material and film perform an incline movement within a range of 30 to 50° to the front and back on the axis.
2. Revolving type.
On one side of this apparatus there are set up two sticks (one is 3cm in diameter the other being 10cm) and on the other side, the third stick is installed 10cm long with the handle to rotate itself. Between the first two sticks and the third there is a distance of 40cm and these sticks are so connected with a belt that they can move at the same speed simultaneously. A film is placed on a lower stick and a material on the taller one or the process can be reversed. In any case, the three sticks revolve at the same speed in one direction while being exposed to X-ray radiation (Fig. 1).
Our initial purpose of a set of experiments was to extract a layer of tissues on a film from among many structure layers and we were successful in it. Further, we also succeeded in the traverse and transverse tomographic section of the head of a rabbit.
Our attempt to take a tomographic section of the tooth, however, failed, for we used an ordinary dental film. But it is hoped that, with the future refinement of these apparatus and attendant techniques, better results will be obtained to aid us in our daily laboratory work more accurately and cheaply.

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This report discusses certain kinds of pollution caused by chemical fertilizers. It also considers how these problems may be minimized or avoided by using compost instead of chemical fertilizers. Particular attention is devoted to fluorine contamination because this element, which is present in phosphatic fertilizers, is a health hazard. That is why the Swedish Parliament, on November 18, 1971, revoked the law allowing communities to fluoridate their drinking water. Fluorine is, among other things, a carcinogen. It is therefore important to minimize our total daily fluorine intake. A more extensive use of compost can help us do that because it has a very low fluorine content.

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