Germ plasm

“ Even a very minute trace of a specific germ-plasm possesses the definite tendency to build up a certain organism, and will develop this tendency as soon as the nutrition is, for some reason, favoured above that of the other kinds of germ-plasm present in the nucleus."
In place, then, of the direct continuity of germ-cells as distinct from body-cells, we have here the direct continuity of germ-plasm as opposed to body-plasm. The germ-plasm can give rise to body-plasm to any extent; the body-plasm can never give rise to germ-plasm. ”

“ Under the former theory the germ-cells are no longer looked upon as the product of the parent’s body, at least as far as their essential part—the specific germ-plasm—is concerned: they are rather considered as something which is to be placed in contrast with the tout ensemble of the cells which make up the parent’s body, and the germ-cells of succeeding generations stand in a similar relation to one another as a series of generations of unicellular organisms, arising by a continued process of cell-division. ”

“ The body of the mother, indeed, seems to serve merely as a protective envelope and a source of nutrition.
Effects of Body on Germ-Cells General, Not Specific.—As far as the evidence regarding the modification of the germ-plasm by the body is concerned, we must conclude then that while under special circumstances the germ-cells may be affected, the effect is general rather than specific and the result as seen in the offspring has no discoverable correlation with any particular part or structure of the parental soma. ”

“ Germ plasm is not something apart from or uninfluenced by all that goes on in its immediate environment within the body. Regression and dedifferentiation involve reconstitution and always approximate reproduction. ”

“ The only thing that makes any knowledge unpractical is our more or less temporary ignorance of how to apply it. The first question which instantly raised itself was, "How did the plasmodium get into human blood?" The very sickle-shape of the plasmodium turned itself into an interrogation mark. The first clew that was given was the new and interesting one that this organism was a new departure in the germ line in that it was an animal, instead of a plant, like all the other hitherto known bacilli, bacteria, and other disease-germs. ”

“ It is also accounted for by the germicidal properties of the blood serum.
The resistance of the tissues may in some cases be due to the absence from them of some particular element necessary to the growth of a particular microorganism. This refractoriness varies in every species of animal in its relation to every form of germ. Different individuals of one species also vary in their susceptibility, and even different parts of the body vary in the same individual. The lower animals offer a greater resistance to pyogenic bacteria than do human beings. ”

“ The later system of Pasteur is founded on this same general truth, as are also the methods of lessening the pathogenesis of germs by subjecting them to compressed oxygen, to graduated heating, to an altered chemical condition of the culture medium, to antisepsis, etc. For a time such weakened cultures often retain their lessened pathogenesis, even through a succession of cultures in a susceptible animal body, acting as if the germ were indeed a distinct species. ”

“ The young specimens of the plasmodia, as this particular germ is styled, develop in the red blood cells; and as they grow they destroy their habitation. I could tell you of interesting changes of color in the blood corpuscles, of the active, joyous dancing of the parasite, and of its multiplication by sporulation. ”

“ Sometimes they pass back into the blood stream and carry the bacteria to various parts of the body for elimination. Not infrequently the white corpuscles die in the contest, and then may accumulate in the form of pus and make their way through the skin to be discharged directly. The battle between these phagocytes and the bacteria goes on vigorously. If in the end the phagocytes prove too strong for the invaders, the bacteria are gradually all destroyed, and the attack is repelled. Under these circumstances the individual commonly knows nothing—of the matter. ”

“ He believes that organs in the adult, not necessarily by direct action, but by action from a distance, may alter the germ. Of this, there is no proof at present. Others have suggested that just as the ductless glands pour into the blood chemical substances which materially affect the growth and development of other portions of the body, so similar enzymes, or other chemical substances, may be sent into the blood, which subsequently bathes the germ cells of the coming generation and produces the change. ”

“ From the view-point of cell-differentiation, which seems to me the most tenable position, there does not seem any evidence for, or any probability of, the occurrence of any roundabout mode of development of the germinal cells which could enable them to pick up acquired characters en route.
(d) We come now to the contention that the organism, being one and continuous, if any member suffers, the germ suffers with it. The organs of the body are not isolated or insulated; the blood is a common medium; the nerves ramify everywhere ”

“ The blood corpuscles of man and woman are the same, and so are the cells of their nerves and muscles; and even the sexual cells, so different in size, appearance, and generally also in motile power, must contain the same fundamental substance, the same idioplasm. Otherwise the female germ-cell could not transmit the male characters of the ancestors of the female quite as readily as the female characters, nor could the male germ-cell transmit the female quite as readily as the male characters of the ancestors of the male. ”

“ They do not, however, occur in the tissues of a healthy individual, either in the blood, muscle, gland, or any other organ. Secretions, such as milk, urine, etc., always contain them, however, since the bacteria do exist in the ducts of the glands which conduct the secretions to the exterior, and thus, while the bacteria are never in the healthy gland itself, they always succeed in contaminating the secretion as it passes to the exterior. Not only higher animals, but the lower animals also have their bodies more or less covered with bacteria. ”

“ The following statements comprise the most important facts known in regard to it, and its relation to the disease in man.
Undoubtedly the malarial germ has some home outside the human body, but it is not yet very definitely known what this external home is; nor do we know from what source the human parasite is derived. It appears probable that water serves in some cases as its means of transference to man, and air in other cases. From some external source it gains access to man and finds its way into the blood. ”

“ This appears to be due to the fact that the cells concerned in reproduction are set aside during embryonic life and from then on are practically unmodified by the succeeding development and experiences of the parent. In fact, during the lifetime of the individual, the germ cells are so completely isolated from the growing organism that nothing but nourishment in the shape of blood can possibly reach them, hence they can be affected only by a vitiated or poisonous blood supply. ”

“ Any cause that lowers the vitality by depressing the [Pg 12] system, reduces the resistance to bacteria and is therefore apt to favor their growth. Exhausting diseases such as anemia, obesity, alcoholism, diabetes, fatigue, or even exposure to cold, are instances. Germ growth is also favored by the presence of dead, or injured tissues, of blood clots, of foreign substances, and above all, by the presence of some of the substances in which the germ has already been growing at the time of its inoculation, and containing some of its toxins. ”

“ This does not ignore that the chemical products or enzymes which are constructed by the vital activity of the microbes, will dissolve or transform organic matter, but in the absence of the microbe no such enzyme can reproduce nor multiply itself and its action must therefore be exactly limited by its amount. The living germ itself is therefore the one effective factor, by which the contagious disease may be maintained and propagated. In its turn the living germ can only come from a pre-existing living germ. ”

“ Since this time the phenomenon has been observed with a great variety of cells other than red blood corpuscles and bacteria—leukocytes, spermatozoa, cells from liver, kidney, brain, epithelia, etc., protozoa, and many vegetable cells.
It is therefore a well-established fact that the proper injection of an animal with almost any cell foreign to it will lead to the blood of the animal injected acquiring the power to injure or destroy cells of the same kind as those introduced. ”

“ It is therefore possible to conceive that at some time or other there has existed only one kind of germ, that variations from this one type have arisen in consequence of the modification wrought upon different individuals by their chance falling upon this or that degenerate tissue. Variation must lead to specialization, and finally we find diseases all dependent upon the action of germs, as different from one another as one species of animal differs from another. ”

“ After their origin the middle germ layers are differentiated into several fundaments (rudiments) by processes of folding and constricting off.
The development of the connective substance and blood is explained by means of the mesenchyme germs. This is followed by chapters on the establishment of the external form of the body and on the fœtal membranes of reptiles, birds, mammals, and man. ”

“ Thereby would be found a connexion between the modified parts of the body and the germ-cells, the only connexion in existence. It is to be assumed, according to this author, that only a qualitative change in the nutritive fluid of the germ-cells could produce an effect: a quantitative change would only cause increased or decreased nourishment of the entire germ cells. ”

“ The study of the cells of glands engaged in secretion, even when the secretion is colorless, and the comparison of their appearance when secretion is going on with that seen when the cells are at rest, have shown that the cell plasm is much more granular and opaque, and contains larger particles during activity than when the cell is passive; the body of the cell swells out from an increase in the contents of its plasm, and chemical changes accompany the act of secretion. ”

“ The method of demonstrating the germ cause of disease is as follows: Using only sterilized test-tubes, forceps, pipettes, cotton, etc., take a particle of virus, known or supposed to contain pathogenic microbes, from a person suffering from an infectious disease, insert it by a delicate glass pipette through, the sterilized cotton plug of a test-tube containing some of the prepared culture material, and deposit it there. Then place the tube in an incubator, warmed to the required degree, and let it remain for the number of hours suited to the peculiar requirement of its germ contents. ”

“ Methods of fighting Germ Diseases.—As we have seen, diseases produced by bacteria may be caused by the bacteria being directly transferred from one person to another, or the disease may obtain a foothold in the body from food, water, or by taking them into the blood through a cut or a wound or a body opening.
It is evident that as individuals we may each do something to prevent the spread of germ diseases, especially in our homes. We may keep our bodies, especially our hands and faces, clean. ”

“ Isn't this a marvellous picture? To see the micro-organism move, evolve and revolve in the midst of normal cells, uncoil and undulate in the fluids which they inhabit, to see them play hide and seek with the blood corpuscles and clumps of fibrin, turn, twist, and rotate as if in a cage, to see these deadly little trypanosomes moving back and forth in every direction displaying their delicate undulating membranes and shoving aside the blood cells that are in their way while by their side the leucocytes, or white corpuscles, lazily extend or retract their pseudopods of protoplasm. ”

“ From this period they rapidly increase in number, up to the commencement of the formation of the embryo as a body distinct from the germ. Though before this period they probably become the nuclei of veritable cells which enter the germ, it is not till this period, when the growth of the blastoderm becomes very rapid and it commences to spread over the yolk, that these new cells are formed in large numbers. I have many specimens of this age which shew the formation of these new cells with great clearness. ”

“ The germ-cells are distinguished by their large nuclei and their granular protoplasm. The genital organs are only local swellings of the genital rachis, and from the shape of some of the germ-cells it is regarded as highly probable that the primitive germ-cells wander along the rachis and accumulate in the genital organs. ”

“ The process of division goes on especially in the blood-forming organs, and is therefore met with more frequently in the spleen and in bone-marrow than in any other situation. The parasites, at certain stages of their development, may escape from the red blood corpuscles, in which case (especially when exposed to the air for a few minutes) they send out long processes of protoplasm and become very active, moving about in the plasma and between the corpuscles, sometimes losing their processes, which, however, continue in active movement. ”