Volume 1

A text-book of pathology for the use of students and practitioners of medicine and surgery / edited by Ludvig Hektoen and David Riesman.

  • Hektoen, Ludvig, 1863-1951.
Date:
1901
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: A text-book of pathology for the use of students and practitioners of medicine and surgery / edited by Ludvig Hektoen and David Riesman. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    LEC OS A^t. STRIOtNC INTRODUCTION. HEALTH AND DISEASE. The human body consists of cells and of intercellular substances derived from the cells. In the different parts of the body cells of very different appearance and function are met with ; thus we sjjeak of epithelial cells, nerve-cells, muscle-cells, bone-cells, cartilage-cells, blood-cells, connective- tissue cells. Portions of the body made up chiefly of one variety of cells constitute a tissue ; the epidermis is an epithelial tissue, as is also the lining of the alimentary tract; the skeleton consists in part of bony tissue, in j)art of cartilaginous tissue; the heart is made up chiefly of muscular tissue; the skull is filled mainly with nerve-tissue. Tissues of various sorts are com- bined in different ways to form organs; the liver is made up of epithelial tissue, combined with connective tissue, vascular tissue, muscular tissue, and nerve-tissue ; the intestine is composed of epithelial tissue, connective tissue, blood- and lymph-vessels, muscular tissue, and nerve-tissue. All the cells composing the various organs and their constituent tissues have been derived from a single cell—the fertilized egg-cell. Formed by the fusion of a single spermatozoon with a single ovum, this fertilized egg-cell represents the sum of the substances and forces derived primarily from the two parents; that is to say, it is the substratum of the phenomena which we include under the term heredity. The fertilized egg-cell lodged upon a normal uterine mucous membrane and finding there conditions favoi'able to its development, begins to undergo subdivision first into two cells, then into four, eight, sixteen, and later into an enormous number of cells. In its development the fertilized egg-cell—in this case the human organism—is greatly dependent upon and markedly influenced by substances and forces from without it. Not only is this true wliile the organism remains within the uterine cavity of the mother, but also after it has reached tlie world outside of the mother. The influences which affect the organism from without are designated influence's of environ- ment. As far as can at present be seen, the structure and functions of every human organism have to be regarded as tlie exact resultant of the interplay of inherited substances and forces with the substances and foi-ces in the environment of the organism. In all probability no two human beings are exactly alike, for in the first place all evidence is in favor of the view that the individual sjicrmatozoa of a given male as well as the individual ova of a given female difi'er materi- ally from one another; and in the second place, the influences of environ- ment, though sometimes nearly, arc never exactly equivalent for two indi- viduals. It is surprising, not that liuman beings are so different from one another as they are, but rather that they resemble one another in structure and function so closely as we find that they do. If it be true that all individuals differ more or less from one another, the