An attempt to know the principle of control in the living systems by investigators in broad fields of nonbiological disciplines may give rise to the following expectation. The present-day technological civilization has urged every unit component and every unit process of our society to organize into certain purpose-pursuing systems, which have never existed before. Such huge artificial systems have brought about a tremendous development on one hand, but an unexpected transitional chaos on the other, which covers a world-wide range of disturbances to the harmony in our biosphere. Meanwhile, a biological organism exists as a totality, exhibiting a beautiful harmony not only with other external components but also with its own internal components. Consequently, the control principle governing the biological systems may give some valuable suggestions for the construction and well maintenance of artificial systems, through reorganizing our view of value. On the basis of such presupposition, discussions extend to how we can categorize living organisms into systems from phylogenetical, ontogenetical, distributional, morphological, biochemical, physiological, behavioral standpoints and so forth, referring to the integrative role played by the neuroendocrine control system. Then some characteristics of biological systems such as the a posteriori nature which is related to adaptability, individuality and feedback mechanism, the reproductivity and reutility associated with chain-relations and cyclicity, the variety and individual differences, and the incompleteness and nonlinearity related to dynamic stability, are described in comparison with artificial systems. The methodology applied to the analysis and synthesis of biological performances are also briefly reviewed. Finally, the difference between the status of our-recognition and the initial expectation is clarified together with some optimistic encouragement based on an analogy with evolutional history of the living organisms.

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A streaming potential appears in the tip of a glass micropipette when a hydrostatic pressure is applied between the inside and outside electrolyte of the tip. In this experiment, an attempt is made to apply the streaming potential to hydrostatic pressure measurements in limited volume biological compartments.
This paper deals with an experimental analysis of the streaming potential in a glass micropipette filled with NaCl solution. And on the basis of this analysis, some principles are described which contribute to the design of the new biological extrafine pressure transducer. The theoretical equation for the streaming potential Esp is given by the Helmholtz-Smoluchowski equation as follows :
E_sp= (εζ/4πση) P=S_p·P
where P is the pressure difference, ε is the dielectric constant, η is the viscosity, σ is the conductivity of the solution, and ζ is the “zeta-potential”. The equation indicates that, when pressure is applied to the micropipette which is filled with an electrolyte, a streaming potential appears at the tip in proportion to the applied pressure.
It has experimentally been found that the pressure sensitivity S_p is independent of the tip, size, but depends on the concentration C, pH and temperature of the solution. S_p is in proportion to C^-1.2, and, for 0.9% NaCl solution, S_p is about 2 μV/mmHg and its variation for pH and temperature is about +5%/pH unit and +1%/deg, respectively.
As a result of an exploratory biological experiment, a waveform of blood pressure in the iliac artery of a toad is demonstrated.

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The renography has been of an increasing interest in the diagnosis of the renal function. But it is difficult to deduce the renal function from the quantitative estimation of the renograms because of many factors involved. For the practical diagnosis it has been common to classify renograms by observation into several types. The pattern recognition by observation is not accurate ; for the same renogram, sometimes different identification is given by different physicians, even by the same doctor at different times.
This paper describes an algorithm for pattern recognition of renograms with a small digital computer by applying the so-called “Learning Machine” method. The renogram-patterns were classified into 7 types. Of the 7 types, 2 were separated from the others by simple logic. To the other 5 types, the “Learning Machine” method was applied. In our method, 10 linear discriminant functions must be computed to establish the decision surfaces. This enabled our “Learning Machine” to classify unknown renograms into one of 5 renogram types. Moreover, the machine is devised so as to be able to get more appropriate decision surfaces by learning new renograms one by one.
On the first learning, the machine learned 25 renograms, which consisted of 5 typical renograms per each 5 types. When the first learning was finished, the percentage of agreement between machine and specialist classifications was 58 %. When the number of renograms learnt by the machine was increased to 53, it became 90 %. This fact proves that our algorithm is clinically applicable enough.

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Motivation of the studies of human handwriting process is derived chiefly from the realization that the studies of handwriting process have the potential to increase our knowledge of the function and organization of a biological system through the study of a common but sophisticated function of that system.
This report is divided into four parts. In the first part, studies are initiated by designing and constructing a handwriting analyzer by which measurements are made of vertical and horizontal projections of displacement of a pencil-point and writing pressure as well as EMG records of muscle activities in the forearm during handwriting or related movements. In the second part, the equivalent dynamic model of handwriting process is proposed by generalizing the model first presented by D. Van der Gon. In the next, experiments concerning the guiding of human handwriting movements are carried out, in which the equivalent muscular force model is given. In the last, the equivalent dynamic model of handwriting process proposed here is proved to be successful through the synthetic studies of handwriting.

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Several papers on the applications of the nuclear magnetic resonance (NMR) technique-for the biological measurements have been published since the first proposal of the NMR blood flowmeter by Bowman. However, the problems arising inherently from the non-invasive measurements of the specified area in the body were not discussed in these papers. The authors proposed previously the magnetic focusing technique as one of the new approaches and discussed some problems related to this technique.
In this paper, some basic problems of the applications of NMR for the non-invasive measurements are discussed and the fundamental properties affecting the measuring sensitivity attained by the magnetic focusing technique is analyzed. The problems treated and the obtained results are as follows :
1) The relations among parameters such as relaxation times and radio frequency magnetic field which influence the measuring sensitivity are experimentally analyzed.
2) The distributions of RF magnetic field inside or outside the transmitter coil are theoretically calculated. Approximate values of relaxation time of 1-2 sec. and 0.1-1 sec. are experimentally obtained respectively with the various body fluids and tissues of the dog and the human. Philosophy of choosing the appropriate parameters are discussed based on these results by taking the saturation factor in Bloch's equation and the measuring sensitivity into account.
3) Application for the tumor detection is discussed and the differences of 20% and 200% in relaxation time between normal and cancer cases are experimentally obtained respectively with the tissues from the stomach and the breast. Further, it has been found that the relation between hematocrit of blood and its relaxation time was linear.
4) The deterioration of signal output by body tissues is examined by a model experiment. According to this experiment, it is shown that the deterioration of S/N ratio was equal to approximately 30%, at f = 60 MHz.
5) From above results, in the case of applying our proposed magnetic focusing technique, the resolution or the minimally detectable volume of water in the typical organs by S/N of unity at resonance frequency of 60 MHz should be about 0.3 ml.

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A flow limit type blood pressure regulator device made up of a diaphragm and a knife edge for occluding a blood vessel is proposed. In the device, blood pressure is regulated by controlling blood flow resistance by the pressure difference between the intravascular pressure and the reference pressure. This device can be applied to realize a constant pressure load and a constant pressure perfusion. In vitro and in vivo performance of the device is examined by a mock circulatory system with this device placed on the descending aorta of dogs. Experimental results obtained indicated that the intravascular pressure was regulated within ±2 mmHg when the flow rate changed less than 1000 ml/min, and that in the animal experiment, the response time was about 5 sec for rapid changes in blood flow rate or peripheral resistance of perfused organs.

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