A text-book of pathology / by Alfred Stengel.

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of pathology / by Alfred Stengel. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    be furiiislu'd. In the case of certain sarcomata (]ym])hosarcoma) it seems pt)ssible that bacteria are the immediate factors. In carciuomata and other epitlielial new-growtlis, as well as in sar- coma, certain forms of intracellular animal parasites have been described, though the nature of these bodies remains still in doubt; and recently the theoiy is gaining ground that blastomy- cetes are active in the ijroduction of tumors. Upon the whole, though it must be admitted that the infectious nature of tumors is probable, the actual proof still I'emains wanting. In experi- ments upon animals it has beeia possible in a few cases to demon- strate inoculability. The signiiicance of this fact, however, must not be overestimated, and it certainly cannot be assumed with- out further proof that this evidences the infectious nature of the growths. Predisposing Conditions.—Whatever may eventually prove to be the immediate cause of tumors, it is certain that predisposing causes are often of great importance. The occurrence of certain forms of tumors in persons of advanced age and the occurrence of tumors in other persons whose vitality has been reduced by disease give evidence that a constitutional predisposition is some- times requisite for the formation of the new-growth. The nature of this vital defect has sometimes been speculated upon, and retro- grade vital metamorphosis of the cells or other like changes have been assumed to occur. These theories, however, are purely specu- lative. In some cases there is evidence of a family predisposition, and heredity was formerly regarded as of great impoi'tance. While this element cannot be entirely denied, it has certainly been over- estimated. The Structure of Tumors.—In their histologic structure tumors do not differ absolutely from healthy tissues. In all cases they conform more or less with the structure of some one or more tissues. The cells composing tumors invariably represent some one or several types of normal cells, though they may differ in being larger or smaller than the normal cells, or in being of embryonal or undeveloped character. In the arrangement of the cells, however, there is a notable difference, and tumors may be described as being atypical proliferations as far as their organic or tissue arrangement is concerned. The orderly disposition of cells and stroma or intercellular substance seen in the normal tissues and organs is wanting, particularly in the tumors in which organic arrangement is simulated. There may be in some cases entirely typical glandular acini, but the relation of these to each other and the absence of regularly disposed excretory ducts render the tissue as a whole atypical. The structure of tumors is always closely related to that of the tissue from which it springs, a primary tumor invariably grow- ing in a part in which there is some tissue at least of the type
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