The study of biochemical traits, which was the latest frontier in taxonomy only a few decades ago, has become the most active and effective field. Immunological research first began shortly after 1900 (nuttal, 1904), and immunological methods are still used today (Leone, 1964), but many new methods have been added since then. The most prominent is the study of molecular distribution, variation, and evolution. Relatively small molecules, such as alkaloids and saponins in plants, tend to be highly restricted in their taxonomic distribution and can therefore indicate relationships (hegnauer, 1962; Hawkes, 1968). In the case of larger molecules, their evolution can be studied in a variety of ways, particularly through changes in the amino acid sequence. Such changes or differences can often be quantified and used to formulate dendrograms that characterize the phenetic distance. The study of some macromolecules,cosmetic packaging wholesale, such as hemoglobin, lysozyme, cytochrome C, etc., is time-consuming and requires expensive equipment and instruments, and more extensive use requires automated analysis and determination. Biochemical methods are most useful when morphological analysis fails or yields only equivocal results. The use of electrophoretic analysis of enzyme alleles (isozymes) has been particularly interesting (Ayala,Serum Bottle With Dropper, 1976). This method not only reveals a very large number of sister species, but also indicates that the differences between the two species are roughly correlated with the time leading to the separation of the two species along the evolutionary line. Electrophoretic analysis is most effective as an independent check of the results of morphological analysis if it is based on a sufficient number of gene loci. The method of DNA hybridization leads directly to the genotype; in this method most of the genomes of two species to be identified are tested for compatibility, and the degree of matching is a direct indication of the degree of relatedness. Of course, individual molecular traits are just as susceptible to convergence as individual morphological traits. Therefore, it is equally dangerous to establish a molecular single trait classification and to establish a morphological single trait classification. Molecular methods are especially needed to study the junction of higher taxonomic units, such as the order Aves or the phylum Invertebrates. In this regard, morphological analysis has been unsuccessful because a sufficient number of obvious homologous traits cannot be found and the polarity of the evolutionary trend is often uncertain. The results of morphological and molecular analyses are not always consistent, as indicated by the comparison of humans and orangutans. Therefore, some scholars have suggested that there should be two sets of classification, one based on morphological traits and the other based on molecular traits. This suggestion seems ill-advised for a variety of reasons; not only because different molecular traits may require different molecular classifications, but also because it implies that there are several phylogenies, Amber Dropper Bottles ,30ml dropper bottle, which is clearly wrong. Classification is not the classification of individual characters of organisms, but the classification of organisms as a whole. Merging morphological, behavioral, and molecular trait findings into a single, optimized taxonomy will be the task of future integration. Epistemology of classification Philosophers have traditionally expressed some concern about the principle of classification. Indeed, classification (though not in terms of biological classification per se) is one of Aristotle's central concerns (see Chapter 4). The replacement of descending classification by ascending classification in the post-Linnaean period was a major advance in philosophy; 19th-century philosophers, such as mill, jevons, and the Thomists, still showed great interest in classification. However, philosophers did not seize the conditions and opportunities created by the Darwinian Revolution to make the necessary conclusions on biological classification. They are still almost uniformly clinging to essentialism and other archaic concepts that have been abandoned by evolutionary thought. For example, they are confused about identification and classification, regarding classification as a process of identification involving individual specimens, while in fact classification studies populations (species), and individual organisms are only assigned to species (that is, identified). Even today, some philosophers (Hempel, 1965) still believe that "classification is the division of large classes into small classes" (descending classification), although in fact evolutionary classification is the classification of relevant taxonomic units into higher taxonomic units. The most serious flaw in the view of most philosophers is that "the classification of animals and plants …" In principle, it is basically the same as the classification of inanimate objects (Gilmour, 1940:465), and the classification method of the numerical classification school is also based on this same assumption. An artificial or arbitrary classification is reasonable for objects classified strictly according to certain properties or characteristics, such as library books. However, there are certain limitations to the classification of objects for which there is already an interpretive theory (Mayr, 1981). This is true, for example, of the classification of causation of disease and of the classification of organisms based on the theory of relatedness of organisms due to a common ancestor. No meaningful classification can be made of a state of affairs that is the product of historical development without giving due consideration to the historical process from which it came. Classifying the stars, geological phenomena, human cultural components, or biological diversity, as Gilmour suggests, will in most cases not adequately reflect the actual interrelationship of events. Thus, it has been accepted among evolutionary taxonomists since Darwin that natural taxonomic units must be monophyletic, that is, they must be organized by descendants of some common ancestor. This theoretical basis for all biological classification is a powerful constraint and a complete rejection of the view that classification is equally applicable to living and non-living things. A younger generation of philosophers such as beckner, hull,Glass Cream Jars, etc. Have recognized this and are working with biologists such as Simpson, Mayr, and bock who pay close attention to the relationship between evolutionary theory and classification to develop a philosophy of biological classification. 5． Simplification of information retrieval. penghuangbottle.com