Abstract: A plant has no controlling system analogous to the nervous system of animals. Yet when a stimulus such as light or gravity is perceived by one part of the plant, a response frequently occurs in another part some distance away. Experiments conducted over 80 years ago by Charles Darwin first demonstrated this fact and led eventually to the concept of a hormonal control of many phases of plant growth. Plants appear to be almost entirely dependent on hormone-based mechanisms for co-

Abstract: Many lakes the world over are becoming less desirable places on which to live because of nutrient wastes pouring into them from a man-changed environment. Human activities, through population and industrial growth, intensified agriculture, river-basin development, recreational use of waters, and domestic and industrial exploitation of shore properties, are contributing to excessive nutrient enrichment of lakes, streams, and estuaries. This accelerated process of enrichment (cultural eutrophication) causes undesirable changes in plant and animal life, reduces the aesthetic qualities and economic value of the body of water, and threatens the destruction of precious water resources. Overwhelming excessive scums of bluegreen algae and aquatic plants choke the open water, rendering the water turbid and nonpotable. The algae and aquatic plants die and rot, yielding a repugnant odor, and the organic matter from this crop sinks and consumes the deep-water oxygen vital for fish and other animal life.

Abstract: The Panel on the Laboratory in Biology was formed by the Commission on Undergraduate Education in the Biological Sciences (CUEBS) with the charge of clarifying the function of the laboratory in the changing biology curriculum. This paper, the first product of our deliberations, seeks to make a single point which we feel is of such great importance to the future of undergraduate biology that all other considerations in laboratory instruction must be deemed inconsequential beside it. Stated simply, the point is that the best use of the laboratory in undergraduate instruction is to engage the student in the process of active investigation. This paper will be devoted, therefore, to the development and support of the concept of such a laboratory program, which we will refer to as an "investigative laboratory." Additional papers, describing specific investigative laboratory programs in which three of the authors of this paper have participated, will appear separately.

Abstract: Textbooks in biology and biochemistry and general works on the chemistry of natural products devote little space to lignin. The average biologist has a cloudy idea of it as a brown, amorphous material remaining when the carbohydrate fraction has been dissolved out of wood. He vaguely relates it to the equally amorphous humin and perhaps wonders how anyone could possibly find anything of interest in either. Yet lignin demands attention for its sheer quantity if for no other reason about one-quarter to one-third of most woods is lignin, and it ranks behind cellulose as the most abundant natural product. Why, then, has it not been given more consideration?1 Part of the answer can be found in

Abstract: structure and function played a relatively minor role in determining the direction and in shaping the design of experimentation. In the phase of describing phenomena, the conceptual framework is not crucial. It is only when experimentation reaches the interpretative and explanatory stages that permissiveness or indifference with respect to the conceptual framework has consequences which inhibit progress. Within a relatively short time the entire conceptual framework for the study of the mitochondrion has been drastically altered. The concept of what is a membrane underlies the concept of what is a complex of the electron transfer chain; the concept of discontinuous electron transfer is rooted in the concept of the electron transfer complex; the concept of the conformational basis of mitochondrial energy transduction, in turn, rests on the foundation of a membrane continuum made up of nesting repeating units. This pyramiding of new concepts has created the need for a delineation of the conceptual framework within which current research on mitochondria is progressing. It is to the presentation of these concepts that the present communication is addressed.

Abstract: Biologists in general have been happy to leave the study of parasitism to their colleagues who are interested in the parasites of man and of economically important plants and animals. With such interests, these biologists have rightly considered parasitism from the point of view of the host-how to prevent and cure the pathological manifestations of parasitism. However, an approach to parasitism in which the host and parasite are accorded equal importance is capable of producing results of general biological interest.

Abstract: There is a tendency among the public to assume that technology will somehow solve the world population problem through farming the sea and the tropics irrigating the deserts and generating cheap nuclear power in abundance. The facts are that farming the seas is a technology that is far in the future that tropical soils are not suitable for intensive farming and areas which are suitable for intensive farming are requiring immense amounts of fertilizer to keep production high that the world is running out of water and irrigating the deserts will require immense technology and that nuclear power is not cheap and it will be many years before it is abundant. Desalinization techniques exist which could make desert irrigation possible but every day a samll desalinization plant produces enough salt to cover 15 acres of land a foot deep. Getting rid of this salt is also a major problem. Before technology can possibly catch up with world demand active efforts must be made to decrease the mushrooming growth of world population.

Abstract: nutrients to the soil subsequent to planting the site. In studying the shifting agriculture cycle, various workers have made compositional analysis of the second-growth fallow vegetation (Gamble et al., 1967), but little effort has been made to determine the composition of the individual species comprising that vegetation. Nye (1958) determined amounts of plant nutrients in individual species, but only for five elements, and limited his selection to the main woody sp cies in different ecological zones in Ghana.

Abstract: Humid tropical forest ecosystems are among the most complex terrestrial systems on earth in terms of their biotic and abiotic interactions and have a great diversity of taxonomic groups. It is easier to study the whole tropical forest system rather than its component individuals (Feibleman, 1965; Van Dyne, 1966) and its processes of production, decomposition, herbivory, carnivory, parasitism, and symbiosis (Evans, 1956; Odum, 1963) rather than its structure. The structure and composition of forests in eastern Panama, northwestern Colombia, and related areas have been studied extensively by Richards (1952), Cain (1963), Holdridge (1963), Beard (1955), Ruinen (1961), Golley et al. (1962), Espinal and Montenegro (1953), and specifically for this area by Golley et al. in this symposium. The University of Georgia Institute of Ecology, supported by Battelle Memorial Institute, authorized under Public Law 88-609, 88th Congress, performed terrestrial ecology studies in the areas of Panama and Colombia as a part of the Interoceanic Sea-Level Canal Feasibility Study. This report describes some aspects of the movement and storage of stable elements through hydrologic and elemental functions of the Tropical moist forest ecosystem.

Abstract: While the possibility of a sea-level This land barrier is also effective for Atlantic. While the Indo-West Pacific canal somewhere in the vicinity of the marine invertebrates. Haig (1956, undoubtedly serves as the primary Isthmus of Panama has been discussed 1960) studied the crab family Porcelevolutionary and distributional center for many years, its feasibility as an lanidae in both the Western Atlantic (Briggs, 1966), the Western Atlantic engineering project has become enand Eastern Pacific and found that only Region may be said to rank second in hanced as the result of recent experiabout 7% of the species were common importance. Its geographic area is mental work with nuclear devices that to the two areas; de Laubenfels (1936) larger (Fig. 1), its habitat diversity can be used for excavation. It appears found a similar distribution in about greater, and its fauna considerably now that the undertaking of this project 11% of the sponges he studied; and richer than for each of the remaining will be strongly supported as soon as Ekman (1953), about 2.5% for the two regions. Since the Western Atlanthe current economic crisis in the echinoderms. It seems, therefore, that tic species are the products of a richer United States is over. Until recently, only a very small proportion of the and therefore more stable ecosystem, the only facet of the plan that had species in the major groups of marine we may expect that they would prove drawn the attention of many biologists animals are found on both sides of the to be competitively superior to those was the possibility of radiation damage. Isthmus of Panama. The present Panspecies that are endemic to the EastHowever, Rubinoff (1968) finally ama Canal has not notably altered this ern Pacific or Eastern Atlantic. pointed out that there would be other relationship since, for most of its length, An examination of the faunal relaimportant biological effects and gave it is a freshwater passage forming an tionships between the Western Atlantic examples of disastrous invasions that effective barrier for all but a few and the Eastern Atlantic does provide have occurred in other places as the euryhaline species. good circumstantial evidence that results of human interference. With regard to the tropical waters on species from the former are competitiveThe New World Land Barrier each side of the isthmus, there is no ly dominant. An impressive number reason to suspect that each area is not have managed to traverse the open The IsthmusNew World Lanamd Barrier, with supporting its optimum number of waters of the central Atlantic (The narrowthe Isthmus of Panama complete block toing its species. Studies of terrestrial biotas Mid-Atlantic Barrier) and to establish the movement of tropical marine species have indicated that most continental themselves on the eastern side. For between the Western I Atlantic and habitats are ecologically saturated (Elexample, in the shore fishes there are

Abstract: Recent studies suggest that an average biological half-life for a trophic level may be calculated from the transient behavior of radioisotopes introduced into food chains. Following introduction of a radioactive tracer, successive trophic levels show characteristic delays in reaching maximum concentrations. The time required to reach maximum concentrations often is longer for higher-level consumers. The authors have observed such transient behavior in a tulip poplar forest experimentally trunk-inoculated with /sup 137/Cs. Its subsequent redistribution among the canopy, the forest floor, and their associated food chains has been described elsewhere. In successive years, each autumnal leaf drop has resulted in an additional pulse of /sup 137/Cs to the floor of this forest, producing sequential increases and then decreases in the radiocesium content of detritus-feeding arthropods and their predators. Maximum concentrations of /sup 137/Cs reached during transient fluctuations and the time lags between peaks in different trophic levels are related to the turnover rates within each trophic level. Thus, the patterns of accumulation revealed by field sampling may be analyzed to yield estimates of average loss rates for entire trophic levels. This paper provides a model describing such transient behavior and illustrates its application with laboratory and field data. Success with thismore » model using radionuclides encourages us to suggest its application to studies of the dynamics of other constituents in food chains. 17 references, 3 figures.« less

Abstract: The effectiveness of poisonous substances often decreases after they have been in use for some time. This phenomenon, which was apparently known to Theophrastes (Inquiry into Plants, Book IX, Chapter XVI), has caused considerable difficulty to modern man in his efforts to control harmful organisms by the use of toxic compounds. Man has developed very effective insecticides and has been able to apply them economically against insects harmful to agriculture or to public health. However, insects have often developed insecticide-resistant forms which continue the struggle. At least 137 species of insects, mites, etc., developed tolerance to various groups of insecticides by 1960 (Brown, 1961). Antibiotics have been commercially produced and extensively used in the chemotherapy of many bacterial diseases of man and animals. In this case, also, development of resistance disappointed the optimists who believed that, with the use of antibiotics, infectious diseases would become a thing of the past. Familiar with such experiences, the average reader of this article may be surprised to hear that in the control of fungal diseases of plants fungicide resistance has not, to the present time, created comparable problems. The appearance of resistant strains in the field has occurred in only a few cases. The resistance problem seems to have been minimized mainly because of the nonspecific nature of the fungicides used to control plant diseases. From the selectivity point of view, we are far behind in the field of fungicides as compared to bactericides or insecticides. This, of course, will not remain so and, in fact, there is now good reason to suggest that selective fungitoxicants will soon be introduced and become very important in agricultural practice. Fungicide resistance may then become of much greater practical concern and, therefore, knowledge in this field should prove valuable. Fungicide Resistance in the Field

Abstract: ecotype in ecosystem function is primarily one of allowing a community of organisms to adjust to its habitat." The second: "The simultaneous selection of ecotypic variants within different kinds of organisms occupying a given area results in harmonious functions of a particular ecosystem." The third: "The selection of eco-genetic gradients results in the continuity of an ecosystem-type over geographic diversity." These three statements, modified here with reference to ecosystems, were made originally with respect to "ecotypes and community function" (McMillan, 1960). Their application here in reference to ecosystem function was facilitated by the use of the same basic concepts: (a) that ecotype, ecotypic differentiation, eco-genetic gradient refer to genetically-based variation that is habitat correlated; (b) that community is applied to the sum total of organisms in a given area; (c) that population is applied to the one or more individuals of a close genetic lineage in a given area; (d) that ecosystem is applied to the sum total of organisms (the community and its included populations) and to their relations with their environmental surroundings in a given area; and (e) that ecosystem-type results from the lumping or sorting of certain ecosystems into a particular kind. To these basic concepts, a time relation is indicated: at a given time. The modified application from the community to the ecosystem has changed the focus from the

Abstract: "As careful as scientists have been in the design and conduct of technical experiments, they have been overly lax in the analysis of their profession's educational problems" (Darnell and Wise, 1968). In the last decade considerable improvements have taken place in teaching science at the high school level. Yet, many college professors still contend that their courses will be what they are regardless of their students' high school background (Adams, 1952; Montean et al., 1963; Rozolis, 1967). When such views are so common, no wonder that "attempts to improve the transition between high school and college are noticeable in only few universities" (Renner et al., 1965). This paper intends to show that achievement in college is highly related to high school preparation, and therefore introductory college courses should be designed in such a way that the student will be able to begin where he left off in high school and make the best use of his previous education. Procedures

Abstract: In the December 1968 issue of BioScience, an article appeared entitled "Calculation and Miscalculation of the Allometric Equation as a Model in Biological Data" by Jerrold H. Zar. This article, while dealing with a very basic and important problem of data analysis-the question of whether or not to use data transformations in fitting models to biological data and the effect of these transformations-tends, I believe, to be misleading for the biological scientist. Since this journal is read primarily by reseachers in the biological sciences, it is important that some of the assertions in the referenced article be clarified. The discussion here falls into five categories: 1) Choice of model 2) Choice of estimation procedure 3) Comparison of models 4) Interpretation of the comparisons made in the referenced article 5) Some features of iterative least

Abstract: This topic is redundant in the sense that it is unrealistic to think of evolution as a process except in the context of the ecosystem in which it occurs, whether the ecosystem is "natural" or created by the wanton or necessary activities of man, including his program of crop improvement and animal husbandry. Habitat disturbance by man is increasingly a factor in most ecosystems as all of us are aware; it affects evolution in various ways including, for example, the development of organisms that we ordinarily think of as weeds and by extinction, which has the negative effect of restricting the genetic resources available for further evolution, including evolution under the control of man. However, since "Man and Nature" will be considered in other papers, I will not pursue this aspect of the topic. The basic elements of the evolutionary process are known: mutation, recombination, natural selection, and chance loss or fixation of hereditary variation. We also know that evolution is inseparably related to the ecosystem in which it occurs, but we have remarkably little understanding of the complex interactions within ecosystems and their impact on evolution. One difficulty in evaluating this relationship quantitatively is that the interactions vary in time and space, which often makes measurement difficult and estimates discouragingly unreliable. The more we probe into this relationship the more we are convinced that significant progress will require cooperation of biologists of many sorts including, for example, theoreticians with mathematical models that can be tested, physiologists and other experimentalists, and natural historians trained to make critical observations and measurements of natural populations.

Abstract: The development of techniques for the separation and identification of molecular components of various body fluids, tissue homogenates, and extracts has placed numerous new phenotypes at the disposal of biologists interested in judgment of affinities between groups of organisms. A voluminous amount of this literature on molecular taxonomy, while paying homage to the molecular revolution of biology, also bears homage to the typology of Plato's eidos. If it appears that taxonomic typology has been replaced by the concept of a taxon as a representation of a Mendelian population of variable individuals, a review of the literature related to molecular characterizations of taxa will dispel this illusion. The potential importance of molecular studies in the understanding of evolutionary processes and in assessing taxonomic affinities is generally obvious. The primary importance of molecular studies appears to be the increase in the number and kinds of measurable phenotypes useful in assessing affinities. Accepting the potential importance of molecular studies, the following criticism regards the use of molecular attributes of individual organisms in evaluating populations. The debate regarding phenetic or phylogenetic inferences of measured differences will not be considered.

Abstract: In the ferns, as in other groups of plants, geographic speciation is one of the dominant processes of evolution. In modern monographic studies it is necessary to be constantly sensitive to the different ways in which this process may operate and the varied patterns of characters and geography that it may produce. The appreciation of the role of geographic speciation is one of the most important elements in the development of a classification that reflects the evolution of a