gogol

In the essay, "On the Immortality of the Soul," Hume repeats his contention that woman's mental capacities are inferior to those of men. "The inferiority of women's capacity is easily accounted for. Their domestic life requires no higher faculties either of mind or body." Although this statement leaves one wondering whether Hume viewed women's intellectual and bodily inferiority as inherent or acquired, in others, such as the one cited above, there is no such ambiguity, in that Hume believes the difference to arise from nature. Talented written term paper are always online to assist you with essay writing; custom services! It appears that Hume subscribed to a position similar to that of Aristotle and quite in keeping with the European view of women in the eighteenth century: "civilized" woman is intellectually and physically inferior to "civilized" man, and her inferiority is innate. This interpretation receives further support from Hume discussion of justice in his Enquiry Concerning the Principles of Morals. Hume poses the question of one's obligations "were there a species of creatures intermingled with men, which, though rational, were possessed of such inferior strength, both of body and mind, that they were incapable of all resistance, and could never, upon the highest provocation, make us feel the effects of their resentment." His answer is that such creatures should be treated humanely, but that they possess no rights and our actions would not be governed by what Hume calls "the restraints of justice." He insists that this properly describes the relationship between men and nonhuman animals, but does not apply to the relationship between "civilized Europeans" and "barbarous Indians," nor between "civilized" men and "civilized" women. In the case of "civilized" women, Hume explains that although the male superiority in bodily strength is sufficient to maintain their tyranny over women, "such are the insinuation, address, and charms of their fair companions that women are commonly able to break the confederacy, and share with the other sex in all the rights and privileges of society." "Civilized" women, thus, are to be treated with equal justice, not because they show men the error of being so treated through reasoned arguments, or act to show men this error with such courage and resolution that men are able to feel the effects of women's resentment, but rather because of their charms. In A Treatise of Human Nature, Hume discusses a group of natural abilities--intelligence, good sense, judgment, wit, and eloquence--which he categorizes as virtues. All of these are mental qualities, and all are, on Hume's reckoning, innate. custom research paper - order custom research paper draft from scratch by experienced writers! Since these qualities are perceived as virtues by Hume, they are abilities we would expect to find well developed in the Humean moral person. In fact, Hume had earlier characterized Cleanthes as possessing both wit and knowledge and exhibiting fine judgment in treating all fairly.

Although retaining a division between reason and emotion, Hume reverses the Cartesian privileging of reason over emotion. "Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.It is easy to Edit my essay with the advices of educated essay editors! Make your essay error-free! " The Humean moral person is the opposite of the Kantian dispassionate, disinterested, autonomous individual. Given his emphasis on emotion over reason, his attention to the moral importance of relationships between people, and the types of traits ascribed to the moral individual, I believe it fair to conclude that Humean moral theory is feminine, or perhaps more fairly that it is androgynous, with an emphasis on the feminine. In this sense, Hume's moral theory can be seen as more balanced than that of Kant. Whereas Kant excludes emotions from the moral realm, Hume recognizes the importance of a balance of reason and emotion. Whereas the characteristics of a Kantian moral individual are male, the Humean moral person blends female and male traits: is sympathetic but, fair, passionate yet reasonable. It would, however, be premature to conclude from this that the Humean moral person is not "gendered," that is, that Hume perceived women as just as capable of moral goodness as men. As we have seen, women have often been seen as incapable or as less capable than men of reason. Therefore, since Hume's moral individual must be capable of reason as well as emotion, it is not obvious that women will be viewed as possessing an identical capacity for moral development. However, the reverse is not the case for men. Men have not been viewed as incapable of emotion. Emotion, often perceived as an inferior faculty of the mind, has been traditionally credited to women and men alike. But reason, seen as a more developed faculty of the mind, has been attributed only to those individuals seen as most evolved or "civilized"--typically upper-class, European males. Thus the question remains, Is the Humean moral person "gendered"? If we look at Hume's discussion of the moral person, it is clear that he was envisioning a man. He tells us, for example, that "when we enumerate the good qualities of any person, we always mention those parts of his character, which render him a safe companion, an easy friend, a gentle master, an agreeable husband, or an indulgent father.If you seek custom written papers, order original custom paper writing help online! " Similarly, at the end of the Enquiry, Hume presents us with a man, Cleanthes, as his model of the moral individual. It is thus important to determine if his description of the moral individual as male is simply a symptom of the sex bias of Hume's culture which he unwittingly inscribed on his moral theory, or if there is an aspect of his moral theory which necessitates the exclusion of women from the moral realm. It is to this question I now turn.

Invertebrate animals range in size from microscopic worms, free-living and symbiotic, to huge forms such as huge giant squids, which, including their longest tentacles, can be as much as 20 m in length. Within this size range, the variety of forms derives from a combination of various appendages attached to bodies that may or may not be segmented, but that are usually bilaterally symmetrical. Colors range throughout the possible spectrum and are combined in sometimes extraordinary ways. The invertebrates include insects and snails, star-fish and corals, and worms of all kinds--in all, about a million different species. And all of them are consumers.

The term predator is usually reserved for animals that hunt their prey. A lion preys on zebras and antelopes, an octopus often preys on crabs, many spiders prey on insects, and so on. We do not think of zebras or antelopes as preying on grass; nor do crabs that browse on algae or butterflies that obtain nectar from flowers strike us as predators. Nonetheless, in all these cases, a similar function is carried out; this includes locating, and orienting to food, attaining it by capture or simply moving up to it (to graze, for example), and then ingesting it. Predators are simply the most dramatic example of this set of common coordinated behaviors. And underlying these behaviors is a set of common structural features. Notably, there is a nervous system for sensing and coordinating; a muscular systemfor moving, which also demands some sort of skeleton for muscle attachment and for transforming muscular action into mechanical action. And these are all integrated with a functional mouth for ingestion.

The second major group of multicellular organisms, the kingdom Fungi, is usefully discussed now, since it too arose in all probability from the protistan protophyta. But whereas the Metaphyta arose from photosynthetic forms, the Fungi arose from non-synthetic ancestors. The Fungi are eukaryotic and predominantly multicellular decomposers, with diverse types of organization.

The bodies of these organisms are sometimes unicellular, but more often organized into filaments. Each filament is called a hypha; collectively, they make up a mycelium. The mycelium, which may be highly branching, extends into the environment that nourishes the fungus. Typically, as decomposers, the fungi live in moist areas where there is an abundance of organic material. Hence their occurrence in dead wood or the litter on forest floors. But they also invade animal tissues--athlete's foot is caused by a fungus. They are severe problems in terms of food spoilage, since they cause molding of breads and vegetables, but they are also helpful in food production, especially in beer brewing and wine making, which depend on the fermentation of yeasts, and in certain cheeses. The colored patches in blue cheese are the result of fungal growth. In brief, fungi grow just about anywhere there is organic material that can be decomposed. Decomposition occurs through the release of enzymes that degrade substrates in the immediate vicinity of the hypha. These substrates are macromolecular constituents produced by other organisms because such molecules contain necessary building blocks for further growth of the fungi. Proteins supply amino acids, nucleic acids nucleotides, and carbohydrates and lipids sugars and other carbon compounds. These smaller molecules are assimilated into the fungal cells and used there for vegetative growth.

Reproductive functions involve sexual reproduction as well as asexual spore-formation. Although the reproductive structures of the familiar puffballs, mushrooms, toadstools, and brackets of shelf fungi are rather complex structures, they constitute the lesser part of fungal growth. The usually invisible mycelium comprises the mass of the organism and is quite simply organized. Only in the reproductive structures does complexity approach that seen in the thalli of the red or the brown algae, for example.

The answer seems to lie in the realization that for freshwater algae--the green algae are the most common freshwater forms--their habitat, when it consists of shallow ponds or streams, often, and even annually, dries out. Adaptations for surviving desiccation would be advantageous, and such adaptations would be preadaptations for living on land. When we consider the evolution of green algae in such terms, it is not improbable that terrestrial forms evolved. But we have no fossil evidence or other data to document that evolutionary breakthrough. There is a gap. It could well be another case of tachytelic evolution, wherein a form adapted to one adaptive zone invades a new zone, evolutionary changes are rapid, and no fossils are found. Furthermore the intermediates are not really successful aquatic plants nor are they successful land plants. They lose out in competition to both. Hence, no intermediates survive. But we cannot, from present information, document Lignier's hypothesis.

This again illustrates the frustrations of phylogenetic research: the concept of evolution encourages us to look for phyletic series, but the action of natural selection tells us we must both expect and accept gaps. Perhaps the most disconcerting aspect of such a gap is our lack of insight into how the primitive transport tissue--the stele--of Rhynia arose. It is disconcerting for two reasons. First, despite the relative simplicity of the rhyniophyte stele (it is a thin strand of long, slender cells in the middle of the stem), it makes a rather sud-den or genuinely neosemic appearance. It cannot be homologized with any green algae cells. Such apparently sudden and discontinuous changes, as we have emphasized, are inconsistent with the known process of evolutionary change. We can only hope that new data from living or fossil plants that represent a useful missing fink here will become available. The second reason is the origin of the nonvascular plants.

Asteroxylon shows stem-like structures that clearly look as if they extended into the soil. In the club mosses we see genuine roots. They have the specialized structures and associated functions characteristic of roots. Some place in the line of evolution between Asteroxylon and Lycopodium, real root structures evolved. This appears neosemic because we look at the ends of the series, i.e., forms without true roots and then forms with roots.

The tracheids of the vascular tissue were evolving throughout this sequence, going from annular through helical and scalariform to ones with bordered pits and, eventually, to vessels. Rhynia has annular tracheids. Asteroxylon has helical ones; the lycopods and some ferns have scalariform ones; bordered pits are frequent in seed plants; and vessels characterize flowering plants. Furthermore, it is important to know that in the embryonic development of plants, annular, helical, and scalariform tracheids can all appear, and in that order. It is clearly a case of an evolutionary history persisting in the development of an individual. In the nineteenth century, Ernst Haeckel pronounced this to be the Biogenetic Law. As we said earlier, further work has shown many exceptions to this "law," but here, in tracheid development, is one of its more obvious manifestations.

Also regarding vascular tissues, there is convincing aposemic evidence in the changes shown by the organization of the xylem and phloem, the significance of pith, etc. These details cannot be covered, here, but are amply documented in texts that cover plant anatomy and its evolution. (See references at the end of this chapter.) Finally, it can be noted that certain flowering plants, such as certain cacti, entirely lack vessels. This is another case of simplification through reduction and loss.

Last, we consider the evolution of gametophyte and sporo-phyte stages. In the sporangia of the lycopods there is a gametophyte stage, but whether gametophytes occur in Asteroxylon, Sawdonia, and Rhynia is still conjectural. That is, although there is every reason to believe they occurred in those plants, they have not as yet been identified. A different problem is the two different patterns of occurrence of gametophytes and sporophytes in the ferns and club mosses. In the ferns, there is a separate plant for each stage; in the club mosses, the gametophyte develops within the sporophyte, as it does in the seed plants. In ferns the situation appears to be a dead end--it has gone no further than what we see. The ferns are an example of homosporous plants, i.e., plants that produce only one type of spore. This spore germinates into a gametophyte with male gametes in its antheridia and female gametes in its archegonia.

The two metaphytan algal phyla have separate origins. What about the rest of the Metaphyta, the multicellular terrestrial plants? Again, from information given earlier, we see good evidence for homologies in the pigments, photosynthetic products, and cell walls of these plants and the green algae (Chlorophycophyta). The problem now comes down to locating a plesiomorph for the land plants and then seeing if it can be homologized to any of the multicellular, aquatic green algae.

One outstanding candidate for the plesiomorph of the vascular land plants is Rhynia gywnne-vaughani. This is a fossil plant of the Silurian and Devonian periods of the Paleozoic (about 400 × 106 years ago). This plant is described by paleobotanists as a leafless, rootless, branching stem. Part of the stem was prostrate on the ground and from it there extended tufts of slender filaments--not roots--into the ground. Presumably they took up water and minerals. The aerial part of the plant had only one specialized structure at the end of some of the stems, interpreted as sporangia, for the formation of spores. Within the sporangia are the expected tetrads of cells, a characteristic of spores. These structures identify the plant as a sporophyte. Stomata are seen on the stems and this suggests that the stems were photosynthetic. Furthermore, the fossils are so well preserved that a very simple vascular bundle, or stele, can be identified in the center of the stem. Tracheids of the stele are even identifiable as annular. They make up the xylem, and surrounding it is the recognizable phloem.

Except for such plants as the duckweed Lemna, no other vascular plant is as simply organized as Rhynia. In the case of Lemna, there is every reason to think of its simplicity as being due to a reduction of parts from much more complex plants.

Now Rhynia as a plesiomorph poses at least three problems: (1) How did more complex vascular plants, with roots and leaves and gametophyte as well as sporophyte stages, arise from it? (2) What was ancestral to Rhynia? (3) Rhynia maywell be the plesiomorph for the vascular plants, but what about a plesiomorph for the nonvascular mosses and liverworts?

Flowers are now widely interpreted as being a stem with variously modified leaves. Actually, a better interpretation is to compare a flower to a young shoot with leaves in various stages of development. The Russian botanist Takhtajan, from the Botanical Institute in Leningrad, makes a convincing case for flowers as neotenous structures. By that he means they are stages of early development that persist into the adult. Or, conversely, that (sexual) maturity has arrived early. In the case of flowers, Takhtajan and others before him have concluded that flowers are derived from leaves. The green sepals--obvious at the base of roses, where the flower arises from its stem--are especially leaf-like. The venation (arrangement of veins) of petals is often reminiscent of leaf venation. And even such specialized structures as stamens and the pistil have leaf traces extending into them. Commonly, flowers are dioecius, since they contain both male and female reproductive parts--they produce the male gametophyte from the pollen and the female gametophyte or embryo sac from the megasporocyte. However, some flowers are monoecius, with flowers of each sex occurring on different plants.

Aposemic traits are most informative when we come to tracing the course of evolution. Neosemic traits are also useful, but more so as markers for the initiation of an innovation than for tracing lines of historical development. In the foregoing summaries of structures and life cycles, it became apparent that the Metaphyta show a number of aposemic or variable traits as well as certain neosemic ones. And among neosemes, such as vascular tissues, seed, and flowers, these also show aposemy. According to the methodology for phylogenetic analysis given earlier, once homologies have been identified by positional and compositional relationships (direct similarities that identify plesiosemes) and by serial relationship (indirect similarities that identify aposemes), we must proceed to the designation of a plesiomorph. (Neosemes show no homologies.) The plesiomorph is the actual form (fossil or living, embryonic or adult) that most closely resembles the ancestral form or forms of the group or groups in question. Let us now look for one or more metaphytan ple-siomorphs, and then, from that starting point, see what can be said about evolutionary trends, in general, and phylogenetic relations, in particular, within the Metaphyta.

There are clear parallels between the gametophyte and sporophyte stages of cone-bearing and flowering seed plants. Both produce small, haploid, male and female gametophytes that depend on the parent sporophyte for survival. The seed contains an outer layer of parental tissue around endosperm and embryo. The diploid embryo is the start of a new sporophyte. The endosperm is derived from the haploid megagametophyte in conifers, but from new triploid tissue in flowering plants. Thus, the endosperms are not homologous in conifers and flowering plants.

Now we will consider stems, roots, and leaves before turning to a more detailed consideration of flowers. The stem supports a plant and connects roots and leaves. Hence, it has two principal functions: (1) support and (2) transport of metabolites. Transport is carried out by the vascular tissues of xylem and phloem; support depends largely on highly developed cell walls. Figure 12-7 illustrates vanous kinds of tracheid cells present in the xylem of vascular plants. In the confiers, tracheids with bordered pits are most common. They also occur in the flowering plants, but most commonly there is another cell type called vessels. These are tubular structures aligned end to end. Originally, these were single cells, but their boundaries disappeared where the adjacent cells touched, and the final result is a continuous transport tube.

The many arrangements possible for xylem and phloem will be omitted here, as will further details on their development in young plants. Both are intriguing topics, but of more relevance to the anatomy and detailed phylogeny of various seed plant taxa then to the larger overall trends being surveyed here.

Worth mentioning in regard to stem patterns and vascular tissues is the presence of nodes and internodes. Nodes are the sites of branching of stems and internodes are the intervals between these sites. In the fern, leaf traces in the xylem are correlated with the presence of side branches in the stem. In the seed-bearing plants, the association of the central cylinder of conducting tissues is often interrupted by traces connecting with branches or leaves. The patterns formed by these connections vary systematically with different groups of plants. For example, ferns often show only one trace to one of the lateral extensions of the fronds; in conifers, there are onetwo; and in flowering plants, there are one, three, five, or more. In the flowering plants, the occurrence of one trace is thought to be reduction, by fusion, of at least three traces or loss of two out of three traces.

Pine trees and fruit trees are examples of seed-bearing vascular plants, and fruit trees are also flowering plants. Let us start with an examination of their sporophyte and gametophyte stages, and then discuss the major features of their stems, roots, and leaves, ending up with a special consideration of flowers.

Pine trees have both pollen-bearing cones and seed-bearing cones. Because of these cones the trees have their common name of conifers, or cone-bearers. The cones can occur separately, on different trees (a dioecious or "two-house" condition), or together on the same tree (a monoecius condition). In any case, the two kinds of cones are separate structures. In each there occurs a haploid stage of development in the production of pollen and eggs and this is all that now remains of what we found as a gametophyte generation in ferns, mosses, or green algae. In the male, or pollen-producing cones, there are microsporangia. These are special structures located on the highly modified leaves that make up a cone. Within the microsporangia there are special cells called microgametocytes. (Their larger counterpart in the seed-producing cones are called, for obvious reasons, megagametocytes.) Meiosis in the gametocyte, followed by further special development, results in special pollen grains, each with two hollow sacs. These sacs help make the pollen airborne. numbers of pollen are produced and, when ripe, are wafted by air currents. When pollen land on seed cones the ovules of which are ready to be fertilized, the pollen stick to the ovular openings and germinate. They proceed with development of a pollen tube and its special nuclei. This haploid structure is the male gametophyte, or microgametophyte. The female gametophyte, or megametophyte, lies within the megasporangiumof the seed cone. This seed cone is the familiar pine cone composed of woody scales set in a helical pattern around a central stem. On the upper surface of each scale there will develop two seeds, which contain the new sporophyte; these are also edible pine nuts. Each developing seed comes from the megasporangium and its megasporocyte. The latter undergoes meiosis, and of the cells so produced one from each four becomes the haploid megagametophyte.