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The article presents three classroom procedures for presenting the concept of "mechanism" in biology. The term "mechanism" used in this article refers to the biological phenomena that can be accounted for a series of cause-and-effect relationships. The basis of this paper is the prevalence of anthropomorphic and teleological explanations. Each of the three classroom procedures described includes a paper-and-pencil exercise. The author of this article discusses the importance of clarifying the concept of mechanism, especially pointing out the fallacy of teleological explanations.

The article focuses on several research papers related to the mathematical point of view in biology. An article in one of the issues of 1967 assured that biologists need not fear from the invasion of their field by physical scientists and mathematicians. Researcher D'Arcy Wentworth Thompson invoked simple physical, and mathematical principles by formulating and interpreting the impact of physical environment particularly on the form or structure of living beings. Another researcher named S. Ulam came up a set of ideas concerning the general question of evolution of complex geometric forms from simple recurrence relations.

An action spectrum for the light-induced viscosity changes of Helodea densa protoplasm is given. Only the short-wave regions of the visible spectrum between about 390 mμ and 520 mμ have any effect on the protoplasmic viscosity. Within this area two peaks are found, one at 450 mμ, another at about 470 mμ. A comparison made between this action spectrum and that for the phototropic phenomena argues in favour of a close relationship between the light-induced viscosity changes and the visible phototropic and light-growth phenomena. Probable connections between the two phenomena are discussed. [ABSTRACT FROM AUTHOR]

The article offers information about the programs of the Office of Biological Education (OBE) of the American Institute of Biological Sciences Inc. (AIBS). OBE's office staff and the Commission on Undergraduate Education in the Biological Sciences (CUEBS) monitor educational statistics, government bulletins, journal publications and conference reports for information relevant to education in biology. It addressed issues related to bioscience. The existing programs include visiting biologists programs, consultant bureau, career guidance and student chapters.

Information about several papers discussed at the XVII General Assembly of the International Union of Biological Sciences (IUBS) held in Washington D.C. on October 1970. During the event, attendees passed the institution's first three resolutions endorsed by the International Council of Scientific Unions (ICSU).

A new method for measuring preferences for number of children is presented and related to the subsequent fertility of a panel of married women over a five-year period. TheI-scales, developed on the basis of unfolding theory, reflect the individual's utility function for children. They differ from global stated preferences and are more fine-grained measures, sensitive to variations from a first choice. Scales obtained at an initial interview were found to be consistently predictive of fertility in the prospective period, net of a number of other variables usually associated with differential fertility. Their potential both as independent and dependent variables in research is discussed. [ABSTRACT FROM AUTHOR]

The article examines some general problems relative to the origin of life on earth. Living things maintain metabolic processes that chemical reactions in which compounds of one kind are absorbed by living things. Animals absorb compounds containing high free energy and excrete those with lower free energy. This dynamic metabolic process is an exceedingly important characteristic of living things. Living organisms are able to produce additional living organisms of a fairly perfect or at least operative kind and make allowance for the destruction of organisms that have been damaged or degenerated.

The article presents a study which discussed the children's concepts of reproduction. The author said that the results of this study offer little support for either Freudian or Piagetian theorizing about what the young child thinks of reproduction. There was also no evidence of castration fears or the belief of the universality of the penis. The children did not seem anxious in the interviewing situation. Insofar as the cloacal theory is held by children, it is more likely because of a lack of labeling and a lack of relevant visual and tactile experience.

1. It is shown that cambial activity in seedlings of P. silvestris is maintained longer under 15-hour photoperiods than under 10 hour photoperiods. Similarly, cambial activity may be prolonged in the autumn of the natural photoperiods are supported with artificial illumination to give a 15-hour photoperiod. Hence natural changes in day-length in the autumn appear to control the duration of cambial activity in P. silvestris. 2. In the spring the initiation of cambial activity occurs under both long and short days provided the new annual shoot is allowed to develop, but in de-budded plants there is no cambial activity under either long or short days. 3. The breaking of dormancy in plants of P. silvestris in the spring is hastened and facilitated by a previous exposure to cool temperatures. Premature breaking of dormancy during the summer, however, may be induced when the plants are exposed to continuous illumination. The 'critical' photoperiod for this effect appeals to be about 20 hours. 4. After the buds have become fully dormant in the autumn, they are induced to break dormancy only with difficulty and extension of the new new shoot is very restricted. 5. The mechanism of photoperiodism in P. silvestris is discussed, and the hypothesis is put forward that these-photoperiodic effects result from the production of auxin for an auxin-precursor) in the- light, and the formation of an inhibitor in the dark. [ABSTRACT FROM AUTHOR]

The article reports that the effect of day length on the dormancy of trees has been the subject of investigation by several authors. Researchers gave a good survey of the literature on this subject. Of the many species which have so far been examined, the genus Populus bas never been thoroughly investigated, although several species of this genus showed very obvious reactions to the day length. The plants from short days had some difficulty in awakening even when they were exposed to long days. Only after some weeks did the buds begin to develop.